Where have you heard that the longbow ended Calvary superiority? I don't think that's a widely held belief at all.

There are a couple of assumptions here that can be useful to unpack. Firstly, the example is very localized, other states and empires used infantry much more than cavalry for a long time before and a long time after. Ancient Europe is of course one example, but China is another interesting comparison, even though their success against primarily mounted adversaries did, shall we say, vary. But that is a bit unfair, we can infer that you imply Europe in this question, maybe even Western Europe. But cavalry remained a strong and important part of warfare for many hundreds of years after the Hundred Years War. The Thirty Years War saw large use of cavalry by both sides in the conflict and pop history has latched on to the Winged Hussars of the Polish-Lithuanian Commonwealth for good reason. While infantry rose in prominence cavalry remained an incredibly important and ever-present part in warfare during the entire early modern period.

To the question itself. The impact of the longbow both is and isn't overstated. All the things that u/sansordhinn mention - longbow, crossbow, halberd, early guns - as well as a couple of other weapons like the pike could be thrown into the mix. The fact is it's not the weapon itself that is very important but the capability to muster, train and, most importantly, pay large amounts of infantry. Disciplined, well-led and well-trained infantry showed time and again that it was possible for infantry to defeat cavalry in combat - the Swiss were especially deft with the pikes. While armies dominated by infantry were ridiculosly expensive as well, they had several advantages over knightly armies: They were cheaper man for man and could recruit from all classes leading to larger armies, disciplined infantry often won out over cavalry, sieges were easier with infantry and, not to be forgotten, it put power in the hands of the state and removed it from the nobility. All of these have been put on different levels of importance by different historians. I would argue that the last reason I mentioned has been given not enough importance, but then again one of my specialties is the growth of the bureocratic state, so I might be biased.

So in short: cavalry never really stopped being important and their superiority ending was more of a process than a singular event, even a lengthy one. Infantry rose to prominence for a host of reasons of which new types of weapons was really only suggestive of the greater capability of states to keep large amounts of infantry - the weapons were a result of this development more than a cause for it.

You might be interested in the answer given in this post by u/valkine as well as this post involving u/WARitter and u/rittermeister. The positioning of the english forces and the impatience of the French certainly played a major role in the outcome of crecy and agincourt. The use of obstacles to let infantry to defend successfully against a heavy cavalry charge wasn't particularly unique and there's a good chance that had the english been armed and trained with crossbows or handguns instead the outcome of those battles would have been the same. After the hundred years war ended French tactics did revert to being based around mounted knights, including the estabilisment of a small standing army of cavalry. The lesson was that infantry could be very effective defensively but they were still slow and difficult to take on the offensive, conduct raids, or quickly deal with rebellions.

The late 15th and 16th centuries saw a more significant decline in the role of heavy cavalry as the growing use of disciplined, mobile pike squares, later backed up by ever more effective firearms, allowed infantry to go on the offensive and hold their own against heavy cavalry on any terrain, without having to rely on natural or prepared obstacles. However it was still true that infantry that had no cavalry support was at a major disadvantage against infantry that did, so as long as the gendarmes could drive off the enemy cavalry early on there was still a good chance turn the tide or force the enemy to withdraw. On occasion even pikes still weren't enough to ensure victory against a cavalry charge. At Marignano in 1515 for example, the French Gendarmes went toe to toe against Swiss pikemen and eventually came out on top. The final decline of the traditional heavy lancer in western europe had more to do with the growing popularity of wheelock pistols in the late 16th century which allowed more lightly armored horsemen to hold their own against the heavy armor of lancers without needing the extensive training needed to wield such a long, heavy lance and remaining much more versatile.