This is an enormous question, but a good starting point might be around the rise of identity politics in the mid-late 20th century. Identity politics are, essentially political stances or arguments based upon or informed by one's group identities. It might be argued that an advanced awareness surrounding language and its potentially harmful effects arose from an effort to change social realities by modifying the language used to describe them; this effort was certainly tied to the growing consciousness that individual groups in question had of their own identities and power.

Black feminists, in particular, played an enormous role in beginning to disseminate these ideas both in academia and in their personal social circles. "Intersectionality" is a term to pay attention to, and that these feminists theorized and coined; that's the idea that a person's experience cannot be neatly summed up by using just one aspect of their identity. For example, the black female "experience" cannot be understood solely as a black experience, or as a female experience. Rather, our experiences and the systemic oppressions we encounter are a result of the intersections of many identities and oppressions. Put another way, "the experience of being a black female cannot be understood in terms of being black, and of being female, considered independently, but must include the interactions, which frequently reinforce each other."

So to sum it up, a good starting point for your question would be to look at 1960s and 1970s feminist and social theorists.

Some of Carlo Ginzberg's The Cheese and the Worms might be relevant to your question. The book is about an Italian miller named Mennocchio who was tried and executed for his heretical beliefs during the 16th century. Mennochio’s beliefs and persecution were both part of larger processes; his ideas sprang from a materialistic peasant religion resistant to religious dogma while his persecution took place in a broader trend of the ‘reconquest’ of the masses across Europe following the Peasant’s War.

Mennochio’s beliefs are demonstrated to have not been informed by contemporary heretical sects but were relatively widespread, however they were further shaped by his selective readings of certain books like the Travels of Sir John Mandeville and perhaps the Koran. Ginzberg implies that his essential beliefs were an expression of a fundamentally pre-Christian peasant approach to religion, shaped by the books that he read and his own use of logical thinking.

Now I won't go into details about this miller's cosmology, but the most relevant section is Mennocchio's discovery of religious relativism. Throughout his inquistional record, Mennocchio claims that he is only a faithful Christian because his grandfather was too; if his grandfather were a Jew or Muslim, he would be just as faithful to that religion, a claim that would have obviously been quite shocking during the Counter Reformation. Using the Fable of the Three Rings, he argued to the inquisitors that God loved Jews, Christians and Muslims equally because they were all his children and that all of his contemporaries believed they represented the true faith simply because they were born and raised that way. This fits into his distillation of religious dogma into what was essentially a code of morality; it didn't matter if you were a Christian, Jew, Heretic or Muslim as long as you were a decent person and didn't harm your neighbours.

This 16th century miller from an Italian village had basically discovered religious relativism, at a time when religious denomination was the primary locus of identity. Now the interesting aspect of Ginzberg's argument is that Mennocchio's beliefs were not isolated. They were simply a recorded instance of widespread agrarian belief system that was unique in that he selectively absorbed information that confirmed his beliefs from print literature. This means that while Mennocchio certainly discovered the disturbing fact that people are only religious because they enculturated, he probably wasn't the only person in the 16th century or even the medieval era who thought that way. Now this isn't an example of 'political correctness' as we would define it, and I'm sure people will get upset that I'm giving an example of religious and not cultural relativism, but you have to keep in mind that religious identity was super important during this period which makes Mennocchio's claims very significant.