For racism, you have to understand that modern racism as we understand it is a relatively recent invention. The idea that humans are divided into biologically determined (as opposed to climatologically determined) and hereditary categories is relatively recent; to make an incredibly long and complicated story short, our modern conception of race originates sometime in the 17th or 18th century, and was only fully articulated as a system of pseudo-scientific anatomical "fact" in the 19th. Part of the reason that this articulation took so long had to do with gaps in scientific theories; before you could have a hereditary notion of race, you had to have a theory of heredity, in which traits could be passed from generation to generation (before modern racism, there was already some belief in the importance of heredity, in that the nobility was believed to be physically superior, but there was no rigidly codified theory to explain how this occurred). Recall too the belief in monogenesis (i.e., that humanity was created once and in a single place) was pretty widespread among European thinkers; a few proposed polygenesis (that Africans and other races were separate, inferior creations, not descendants of Adam and Eve) to justify racism; others proposed that Africans were the cursed descendants of Ham; still others, perhaps more "scientifically," proposed that black skin was a hereditary virus.

That is not to say that xenophobic feelings did not exist before modern European racism. That is not even to say that other racisms did not exist. Canizares Esguerra argues that a different sort of racism existed in Spanish colonies before the scientific revolution, one based more on Aristotelian ideas of humors than precise anatomical knowledge of the body. Recall the authority that astrology held in previous centuries; early Spanish colonists and thinkers believed that the Amerindians were inferior to their European counterparts because of the influence of American constellations. This presented a problem for Spanish Creoles (Europeans born in the Americas); if the stars made the Amerindians inferior, wouldn't they likewise make Europeans who spent prolonged periods in the Americas inferior? Again, to make a long story short, the patriotic Creole thinkers appealed to the Aristotelian idea of the humors. The Amerindians were governed by the wrong sorts of humors, whereas the Spanish were governed by the right sorts. The American constellations were actually superior to European constellations; Creoles were superior to both the Amerindians and the Spanish in Spain, because they were governed by the right sort of humor to take advantage of the superior constellations.

Sources: Joyce Chaplin, The British Atlantic World

Jorge Canizares Esguerra, New World, New Stars: Patriotic Astrology and the Invention of Indian and Creole Bodies in Colonial Spanish America, 1600-1650

I don't think this is the kind of question that can be 'answered' in the traditional sense, but I have a few thoughts. I think what it ultimately comes down to, is that in order for something to be opposed and worked against, it needs to exist in the first place. That is to say that the LGBT rights movement could not exist before there was homophobia, and homophobia could not exist before there was homosexuality/heterosexuality. 'Homosexuality' (and 'heterosexuality') as identity concepts came into being in the late eighteen and early nineteen hundreds. That's not to say that homosexual and heterosexual sex didn't exist before then (because they obviously did!) but it was, for the most part, not something around which people centered their identities.

I can speak directly to the LGBT movement, but I think there are some parallels to the others you mentioned. The modern LGBT movement came about in response to the reactionary homophobia of the post WWII era. Societal conceptions of gender, sex, and sexuality are always in transition, as is how societies regulate, organize, and enforce those norms. Although it might be argued that there was an element of the 'perfect storm' in regards to the Stonewall Uprising (and other turning points in social justice movements,) ultimately the LGBT equality movement of the 20th century was a response to conceptual and societal changes in understandings of sex, gender, and sexuality.

It is a huge topic, but I can offer one slice of it. It begins with the Marxist view of class conflict, a struggle between the opressor and the opressed. It is originally entirely economic - that it is based on the structure of production, the owners are the oppressors, the employees (workers) are the oppressed, and originally it all boils down to production technology. To quote Marx "The windmill creates feudalism, the steam mill capitalism." For Marx it was only economic structures that mattered, and culture was secondary: economic structures are the "base" and culture is merely the "superstructure". http://en.wikipedia.org/wiki/Base_and_superstructure

However, just as the article indicates, many post-Marxist thinkers in the 20th century challenged it, and began to see a more complex model of society and a more important role of culture in maintaining oppression and hierarchy. Perhaps the most famous was Antonio Gramsci: http://en.wikipedia.org/wiki/Gramsci#Hegemony although the Freudo-Marxists, the Frankfurter School, French "postmoderns" (Continental Philosophy) also played a role.

Thus the focus of radical intellectuals was more and more a critique of bourgeois culture, not just the economics of capitalism.

Feminism and LGBT rights can be seen as an outgrowth from that, of trying to subvert capitalism by subverting its conservative culture. We can perhaps link it to the 1968 era and the New Left, the counter-culture, where there was more focus on an individualistic subversion of conservative cultural values than on waging a class war against capitalism. http://en.wikipedia.org/wiki/New_Left

Perhaps the clearest intellectual expression of this change from class structure to cultural subversion was that of Herbert Marcuse - http://en.wikipedia.org/wiki/Herbert_Marcuse

" Most important of all, the pressure of consumerism had led to the total integration of the working class into the capitalism system. Its political parties and trade unions had become thoroughly bureaucratized and the power of negative thinking or critical reflection had rapidly declined. The working class was no longer a potentially subversive force capable of bringing about revolutionary change. As a result, rather than looking to the workers as the revolutionary vanguard, Marcuse put his faith in an alliance between radical intellectuals and those groups not yet integrated into one-dimensional society, the socially marginalized, the substratum of the outcasts and outsiders, the exploited and persecuted of other race and other colours, the unemployed and the unemployable. "

However later on the strange thing is that while it all began as a way to subvert capitalist economics through subverting its culture, later on these movements lived a life on their own and actually accepted capitalism - a capitalist businessman who was supportive of feminist or gay causes and led his business accordingly was no longer an enemy.

When Luigi Taparelli coined the term "social justice", he was definitely not speaking about ethnic minorities and the LBGT community. Since then it has become a central tenant of the Catholic Church and many socialist organizations among others, also not referring to ethnic minorities or LBGT.

It has only recently (the last decade), been used this way. While the definition has changed as various groups have co-opted the term, it is most commonly used to refer to worker's rights among socialists and the rights of the poor among religious people.

Source: http://www.firstprinciplesjournal.com/articles.aspx?article=1760&theme=home&page=1&loc=b&type=ctbf