it's basically a big umbrella category for just about anyone of European heritage

I see it differently, white culture is an ideal anyone can aspire to. In my area the majority is Hispanic, but they're white identifying Hispanics like my niece. I'm of Slavic descent personally, not technically a white person. People may see it differently, white nationalists particularly, they definitely don't mean me when they say white people. Different people are more or less strict on their definitions, I personally favor a very wide umbrella

Black culture similarly doesn't really exist and is an amalgam of various African Caribbean and American traditions. But it differs from the so called white culture in that it's derived in the US due to slavery and people were forced together and much of their actual heritage was lost. Over years it's evolved naturally but the differences we see in white and black culture derive from class differences more than anything.

Their actual heritage sucked, but it doesn't mean they don't have a culture, it's just the genesis of a new culture forged from slavery -- which while horrible, worked out to their advantage in the end. I lived with black roomies in college, and they're great guys, but they're not white guys with dark skin. They have their own customs, foods, values, way of talking -- which can be as incomprehensible to me as a cajun patois.

poor blacks and the poor whites

Poor is a euphemism for stupid, and they're definitely correlated, but low socioeconomic status does not mean stupid unwashed peasants and high socioeconomic status does not make a person an "elite" fit to rule over anyone. That kind of thinking is a problem.

We create these shakey foundations when we can't talk plainly and openly about issues, like the idea blacks are only prone to violence because they're poor, so everything becomes about finding socioeconomic solutions because anything else would be "racist." And when you build on a shakey foundation you get absolute garbage results, as we see with the current state of things. Garbage in, garbage out.

And while there are definitely poor dumb white racists, the media casts everyone who doesn't agree with their ideology as hateful, stupid, and racist. Teachers teach that in schools. But it's political rhetoric. Most people start out liberal and grow more conservative. Ideology gets tempered by wisdom.

even enslaving your own people throughout history.

Yeah, the blacks enslaved themselves. That needs to be brought up more too, it fans racist hate to think whitey enslaved their ancestors. Whitey just traded for their ancestors.