People might not be objectively racist, but if you grew up in a school district where the high school of 14,000 kids only had 10 black people attending, you will hear some disgusting stereotypical comments and some very off color jokes eventually whether you are a minority or not. People uttering these things might not even see how damaging these comments are to the groups they target, because they've never met very many of these groups or ever been around someone who would check their behavior. It's just a fact of life when you grow up lacking any perspective of another culture, and the national culture encourages you to adopt biases that aren't rooted in reality, and you have no personal experiences to disagree with them.
People also so kindly forget that the midwest experienced white flight like nowhere else. That sentiment is still in living memory among the older generation.
Yes, white flight was real. One kid I went to school with moved immediately after he had a knife pulled on him, but I don't know any of the details so can't say if it was race related. Our own family moved about a year later. If I had stayed in that house I probably would have went to high school with Prince, but if I checked the yearbook of the suburban school I graduated from I doubt I could find a single black face. I never heard those stereotypical comments you speak of because there was nobody to speak them about.
People also so kindly forget that the midwest experienced white flight like nowhere else. That sentiment is still in living memory among the older generation.