Recently the New York Time had an article "Why Did Racial Progress Stall in America?" in which the effects of the civil rights movement on the progress of Black people was discussed. The conclusion was sobering: In terms of material well-being, Black Americans were moving toward parity with white Americans well before the victories of the civil rights era. What’s more, after the passage of civil rights legislation, those trends toward racial parity slowed, stopped and even reversed.
The authors - who also wrote a book about the subject - seemed puzzled by it. For me it is a logical effect of polarization. As long as everything was quiet people tended to see Blacks just like everyone else. There was no reason to see them different.
Then came the unrest. Not only Martin Luther King, but also more radical Black leaders who claimed that Black were different and who didn't sound very friendly. There was also a lot of news about Black protests that weren't always that peaceful. That changed the picture for many White people. Sure, there might be some points in the Black arguments. But at the same time it was no longer possible to the Blacks as just another human being who just happened to have another skin. And when a situation becomes us-versus-them the default human reaction is to side with your own tribe.
That is also the reason why I find the present "sensitivity" campaigns against blackface, Confederate statues and other symbols so foolish. Study the 1500s and 1600s and you find stories about Catholics persecuting Protestants and burning them alive. Yet nowadays no Protestant will object against Catholic symbols for that reason. And that mutual tolerance was achieved with a phase of hypersensitivity.
You can respect and even admire hypersensitive people. But they will never become your friend and you will always treat them as different.
Fighting racism is simple: just avoid and punish the excesses. For the rest: just pretend that it doesn't exist. Sure, things will take time. But polarization is mainly counterproductive.