Can you not understand why black people would have a problem with slave holders? I don't agree with what they're calling for, but I can certainly understand their perspective. As Condi Rice put it, "I do think that America was born with a birth defect; it was slavery".
I'm not trying to defend it. And you are correct I have but a passing top line understanding of it. OTOH, I do know that BLM was in the streets to protest a very real problem of a racially biased justice system. Even if you don't agree, it's not your experiences that prompted so many to make their voices heard, its theirs.
The problem isn't protests -- it's the looting and BLM's ideology. Police reform is a legitimate cause, but BLM sells the false narrative that black people are disproportionately killed by cops. They aren't. Police reform is something that should be important to all races, because it isn't a race issue. It's an authority issue.