You should check a general reference on slavery across the world (including slavery of Europeans during the late middle ages). There seems to be not a single country whose citizens have not enslaved someone or other at sometime throughout history. I am not as rich as Jeff Bezos or indeed hundreds of thousands of other folk. Now how can you explain that? Answer to your question: yes, a leftist conspiracy.

If you really want some explanations for the lower relative wealth of black households, try reading Thomas Sowell.

https://tsowell.com/