Was this "lion king" story made to depict a lion dominated kingdom look better than a racially mixed kingdom? Are there any sources that prove otherwise?
You need to understand that the Lion King is not a scholarly work. It's a neo-Mufasan work of apartheid apologetics. To understand the film you need to analyze the cultural context of its production. Simba had just restored the ancien regime, and reactionary sentiments were strong in the Pridelands. The hyenas, subaltern that they are, were in no position to make their position heard. Films like the Lion King were common at the time, and its enduring popularity has helped to perpetuate myths about what actually happened that day.
The truth is we don't know. The only established facts are that Mufasa was killed by a throng of agitated wildebeests. It's entirely possible that wildebeests, acting on their own volition, killed Mufasa due to discontent at their assigned role in the so-called 'Circle of Life,' the orthodox ideology and thinly veiled caste system of the Pridelands.
We do have proof: Scar's confession to it.
Though now that you mention it, he may have been forced to. He was in the middle of a battle with Simba, when suddenly Simba got more violent, and nearly killed Scar. One could overhear Simba tell Scar to say something, and then Scar admitted to killing Mufasa. However, it's possible Simba forced Scar to say that in exchange for his life, as his own plot to discredit Scar and usurp the throne.
Simba seemed to be showing mercy to his uncle, but then Scar fell off a cliff and was eaten by hyenas. I wonder if that's a coincidence….
Well, some historians state that Scar was a victim of his progressiveness. The lion society wasn't really ready for such revolution. While trying to introduce race equality, Scar scared the oligarchs, who were used to "traditional society", so they reached out to the son of former king. The rest of the story is well known. Simba overthrows Scar and restores old laws. He also accuses Scar of killing Mufasa and, according to the official version, Scar confesses to it. Although Simba is suspiciously silent about his own escape years earlier.
The only problem is that we do not have any non-regime sources describing these events. Scar's family was forced to silence and pushed out of public life, so as far as I know there is no way to find the truth nowadays.
It's important to bear in mind that extant records from this era are scant at best, with a clear imperialistic lean to the material. Note, I am excluding almost all data from after Simba's crowning, as the "sequels" (as the texts are known) are clearly political and propagandizing in nature, or designed solely for economic stimulus, and are widely considered unreliable.
To analyze the main records from the a bit more in depth:
First, consider the scholarly works of B. B. Rafiki. While elaborate and prolific illuminated texts, the modern consensus is these tomes are psuedo-history at best, with theology, myth and subjective commentary woven through the material. Rafiki enjoyed a high seat in the courts of both Mufasa and Simba, and he makes no secret of his involvements in machinations to bring about the return of the "prodigal prince" (as he was known among the loyalists), even expounding at length on his role in brokering an arranged marriage to the young nobless Nala. Indeed, many scholars today even speculate that the famed "Vision" prompting Simba's change in conscience bears clear evidence of Rafiki's hand, based on his extensive and exhaustive notes of herbology.
Zazu's extensive and exhaustive record-keeping from before Mufasa's death certainly paint the start of a clear picture - the Pride Lands were rich and prosperous, and led with a firm hand - but they also make several facts indisputably clear: first, under Mufasa, and then later under Simba, PL as a nation was governed as a very strict monarchy, one which embraced a rigid caste system, as documented by Mufasa's (in)famous speech late in his reign, focusing on the "Circle of Life." Some have speculated that this may have even been the powderkeg leading to Scar's democratic revolution, as the few fragments left from E.D. of the Hyaenidae hint tantalizingly at a response rally in which a call was made to "Be Prepared." Sadly, the ravages of time - and perhaps revisionist policies - have scoured full records of this rally from history.
It should also be considered that Zazu's notes drop off sharply for several years during the height of the Scarist Era. Notes from that period refer to a length of imprisonment, and surrounding controversy, including larceny and destruction of venatic resources, so it could be inferred he was instrumental in plots against the new government - crimes which were clearly pardoned by Simba's return, which makes his reliability as an impartial scribe rather suspect.
The oral record fares little better. The noted bardic duo, Pumba and Timon, were known to be close compatriots to the outcast prince, and it cannot be debated that the light of his rule shone rather favorably on the pair, earning them lucrative positions at court. A dissenter may argue that their earliest works - especially the seminal epic "Hakuna Matata" - demonstrated their indifference towards the imperial agenda, but that would be neglecting the effect Simba's crowning had on their own home jungle, with the new routes linking it to the Pride Lands ensuring a rich trade of insectile-based nutrients for fresh red meat of vague origins (although the more macabre scholars out there have suggested Crocuta crocuta as a possible source). The evidence is strong that the pair soon elevated their station through lucrative merchantry.
In summary, the records are scant, but many scholars have come to a consensus that Scar's reign was actually a democratic (or even socialist) revolution, twisted by the historians, scholars and imperial record keepers of the restored regime to be painted instead as a simple assassination, uprising and usurpation of the crown.
Perhaps lionizing the leader was necessary to establish legitimacy...
When Lord Aiheu created the world and allocated the creatures to their various roles, he decreed that scavengers like hyenas and buzzards would live on the margins to facilitate their sanitary role but could not otherwise mix with the rest of savanna society because of the filthiness inherent to their character. When Mufasa was assassinated, Scar blasphemed against Aiheu by integrating them into society. After consultation with Rafiki, the only one in the Pridelands with a direct connection to Aiheu and the Great Kings of the Past, I am personally convinced about Scar's guilt in Mufasa's assassination. Several wildebeest also have publicly come forward and begged forgiveness from King Simba for their unwilling complicity in the heinous act, which condemned the Pridelands to years of devastation as Aiheu Himself recoiled in horror from the usurpation of the order of things and the ascension of those slobbering mangy stupid poachers. The proof is in the pudding, I say. Observe:
The historiography of the early Mufasan dynasty is, as several other commenters have pointed out, difficult. We have few sources, and those we have are highly partisan (for example, the almost certainly pseudonymous Zazu histories.) So coming to definite answers is difficult, to say the least. However, there are some things we can say for sure.
The Scar interregnum (see how even the language of this is colored by post-Simban sensibilities) came at a time of famine. There were revisionist attempts by historians in the Simba court to claim that the famine happened after Scar's ascension, but this in fact makes no sense and is pure propaganda - trying to paint Mufasa's reign as a time of peace and prosperity rather than brutal repression. It was famine that led the hyenas (and other of the oppressed classes - wildebeests especially if the Battle of the Gorge is any indication) to a breaking point, such that revolution became inevitable. And as they unfortunately found out, getting rid of an oppressive class can't solve problems that are ultimately natural in origin.
Because for those at the top (lions, their retainers, servants, etc.) the Mufasan reign was a time of plenty, but this was happening on the backs of repressed groups - especially the hyenas. Scar's powerbase among the hyenas and others came from his adopting a populist stance (how sincere this was is a matter of much debate.)
We can see the cracks in the idyllic Mufasan facade; the desperate idea that Scar instigated the riots that led to the Battle of the Gorge where Mufasa died (more post-Simban revisionism), rather than it being a spontaneous peasant uprising (which it almost certainly was.) And this leads us to your question: did Scar assassinate Mufasa?
Obviously the Simbans that came after had reasons to tell this story - it delegitimized Scar, it painted Mufasa in a tragic and heroic light. But at the same time, we have to be careful not to simply take the opposite stance - while it's easy to see Scar as a hero for 'desgregating' the Pride Lands, we shouldn't forget the fact that his reign was also marked by brutal retributions against his political enemies. Like so many revolutions that seek to redress imbalances of class structure (the French Revolution, Soviet Russia), the Scar regime vented an enormous amount of repressed hatred of the lower class for the upper, and he found out that controlling that kind of social outburst is much harder said than done.
So to say that Scar was such an honorable dude that he would never have killed Mufasa is, unfortunately, also a fairy tale. Whether he killed him or not is lost to history (much like Scar's original name - that's effective propaganda).
All we know is that after several years of continued famine (whether due to mismanagement or natural causes, again, we'll never know) Simba returns to press his claim on the throne. He wins a decisive victory (forcing a confession, whether true or not, in the process), and is welcomed back. The famine ends shortly after, and it becomes clear in retrospect and with much help from court propagandists that the bad years are the cause of a bad ruler interfering with the natural order (or Circle of Life, as it was called, though the finer points of Rafikian religion are beyond my area of expertise.)
It's also very much worth remembering the gender dynamics in this case. Spotted Hyena society is matriarchal, to a degree that convinces many casual observers that Spotted Hyena women are in fact men. Lion society, conversely, is patriarchal to an almost archetypal degree. The only thing male lions do is fight amongst themselves for control. All of the actual labour is done by the women.
To understand the threat Scar posed to traditional Lion society we have to understand the roots of the Hyena apartheid. This to goes far beyond simple racist ideology. For example, it can be noted that even in the Mustafan and neo-Mustafan periods there was racial integration within society. What there was not, was any challenge to the patriarchal order. By bringing the hyenas into the pride-lands, Scar was introducing a matriarchal group in the midst of the most profoundly patriarchal society possible. Successful integration of the two social viewpoints might have lead to equality for both. Which would have been totally unacceptable to conservatives in both Lion and Hyena societies.
The question that interests me in the debate as to whether or not Scar assassinated Mustafa, but rather what was Shenzi's involvement? Shenzi in Mustafan chronicles is cast as a subordinate and underling of Scar's until her vicious and murderous betrayal. Does this square with what we know of Hyena society? Can we honestly imagine someone known to be as cunning, controlling, and ruthless as Shenzi simply accepting Scar's orders? Unfortunately conservatives in Hyena society did their work as well as conservatives in Lion society. Shenzi is now held out as an archetypal example of how following male ideas or leadership leads inevitably to destruction, and we're left with no real historical evidence to contradict it.
The Lion King is a bastardized and inaccurate retelling of the true saga of Kimba the WHITE lion. I suggest you familiarize yourself with more accurate sources to learn the true extent of the species-ism.
One thing I was never quite able to follow.
It is fairly clear that the ruling caste has the deeply held religious belief that everything in the land is a part of the "circle of life". The issue I see is that they never confront the cognitive dissonance that occurs when Mufasa's anti-hyena policies attempt to remove them from society, and by extenuation the "circle of life".
It's not a coincidence that SIMBA sings I just can't wait to be king! prior to the event.
Simba wanted it so bad he killed Mufassa unintentionally like a psycho path
The proof that Scar killed Mufasa is dubious at best. Not only were his confession made as a response to physical violence, he also died shortly thereafter, and his followers were banished to live in the outskirts of the Pridelands. The Hyenas and Wildebeests, two other groups who might have claims conflicting those of the simbaists regarding the death of Mufasa are also conspicuously missing from the records after Simbas ascension (Lion King volume 2). Indeed, reading between the lines in this document, the Followers of Scar might have begun to openly question Simbas legitimacy at this point in time, and even the circumstances of Mufasas death. Simbas response to this was to exonerate the Followers of their (supposed) crimes, and a political marriage with their leaders. It should be noted that this only extended to Followers who happened to be Lions.
Records by Timon and Pumba suggest that the Hyenas might have relocated to the jungle beyond the desert. The fact that these rainforests lack the large prey Hyenas prefer indicates this relocation may have been less than volountary. They also appear in far fewer numbers than previously recorded in the Lion King.
The Wildebeests may have suffered an even worse fate than that of the Hyenas. Their special niche in the Circle of Life seems to have been overtaken by unnaturally large numbers of Rhinoceros, the formerly giant herds of Wildebeests are nowhere to be seen, they only appear in small numbers. Did the lions hunt them down as revenge? It is no secret that the famine plaguing the lions under the Scar regime ended after his ousting. Simba may indeed have solved this by overhunting the Wildebeests, conveniently the only group with first hand witnesses of Mufasas death, their numbers now to small for them to dare stand up to the lions.
Oh, wow. What a thing this is.
You have to remember that Simba actually assassinated his father. Scar was patsy to legitimize Simba's rule. Simba was well-read in Shakespearean literature and knew of the Hamlet mythos.