I know there were abolitionists and whatnot but even back then they would often think of black people as 'simple' or 'not entirely human' or whatever. Were there ever people who maybe owned slaves who then grew to comprehend just how terrible their racist actions were and maybe respect minorities on the level that we like to hope most modern white people do? Like where they completely understand that minorities are normal, intelligent, competent human beings and that it was absolutely horrific that they had to endure things like slavery or segregation?
Imagine growing up in a slave owning family, seeing the slaves on the plantation, then having the horrific realization that what your father considers to be 'beasts of burden' are actually human beings just like you who are being treated terribly. I feel like this had to be happening constantly as white people would find themselves in the presence of black people within the racist contexts they were forced into. Not just in a general 'ehh we should just free them and send them back to Africa' sense that a lot of people believed, but in the sense of 'oh my god we are doing an immense amount of harm on these people that will seriously mess them up for generations if we don't immediately start treating them the way we treat whites while also giving them reparations for the damage we've caused their people'.
I'm mainly asking about attitudes towards black people from about the first time they were brought to North America to the early 20th century. If you have something about other races, something from other territories like Canada/Texas/etc, or a later time period that's fine as well.
I can think of one example that sort of fits at the edge of your time span, but it is a stretch to say he understood "the sheer evil of how minorities were treated," but he makes up for that by being a good subject for a book.
I read Ol' Strom by Jack Bass and Marilyn Thompson back when Senator Thurmond was still alive, and I was in grad school with a guy who had been one of his interns.
The tl;dr is that he was in elected office for like 7 decades, so he had the time to start out as about as progressive as an elected (local school board?) official could get away with, then he was as reactionary as his reputation after that, then he 'got religion', coincidentally at about the time the Black vote could determine whether he remained in office, and was often among the good guys of the Republican party in his final few decades.
In his 20s, he was a big supporter of Black education (by local White politician standards.) He used his political office to get the segregated schools better (though certainly not 'equal') funding and was involved in an adult literacy program that raised eyebrows among the Klansman wing of his political world. Long story short - underpaid Black teachers could be paid extra to teach adults after regular school hours. This is not Rosa Parks, but it's better than nothing.
After WW2, when he was a judge, he realized the best thing for his career is sort of like George Wallace, turn it up to 11 with the racism. Then there is the Dixiecrat party, the run for president, bla bla, that everyone associates with Thurmond.
LATER, when the Black vote becomes part of his environment, he pulls back relative to other Southern reactionary politicians. He supported the Voting Rights Act eventually, Black judges, hired substantial Black staff in his own office, the MLK Federal holiday, and did a ton of constituent service and brought lots of pork to South Carolina. No national Republican politician gets as much of the Black vote today as he did in the 1980s forward (though I am sorry I cannot get to the book for actual #s at the moment.)
The book IIRC leaves it as an unanswered question whether he was as progressive he seemed in good decades or as racist in his mind as he acted in the bad decades. He is a product of his incentives and is unique only in that he stayed in office as long as vampires would, like 3 mortal political careers.