re: Why is American History split into Black and White?

It's the chasm between races that causes it to be split. The minority experience and contribution to our history has been often overlooked, so the response to that is to highlight Black history (for example) to make up that deficit.

Which is very evident as so many scream about CRT and try to legally restrict conversations about the Civil Rights Movement and slavery in the classroom. The history of oppression against minorities is deeply entwined with the history of our country and has to be taught of we want children to grow up with any real sense of the world and how we got to where we are today.

When we restrict these realities from being taught, we create two sets of history.

Your question is a perfect example of the cultural schism in America. Conservatives believe that the left perpetuates racism by creating this "chasm" and using it as manipulation to secure minority votes. They don't understand that it is their own inability to understand the importance of recognizing minority oppression, whether in reviewing history or creating policy, that separates us and enables the wealthy to drive it further in order to prevent the working class from joining up together and threatening the power structure.

The history is there. It is fact. It is reality. The alternative history is created when all of this is left out.

It shouldn't offend white conservatives that children are taught the reality that white people treated black people (again, an example. This applies to almost every minority group), pretty fricking brutally for a really long time and that the brutality has effects that still exist today. That doesn't mean that white people are inherently bad, or that there is some sort of guilt that white people today should inherently have to feel about it. A lot of people that we are taught to look up to participated in this oppression, sometimes very actively, that's okay. Life is complicated and there's so much nuance. Recognizing this should not feel minimizing or a personal attack. Society is about overall progress and we frick up and learn. That's totally fine, but we gotta be able to look back at those frick ups to be better.