So, if that link from a few hundred years ago is relevant, is our link to slaving in the past still relevant and worthy of comment?
You get racism and racist everywhere, nowhere is free of it, only laws and socially accepted norms subdue it in those who would otherwise feel free to express it.
As far as I am aware the Arabs mainly, and some indigenous tribes in central and west Africa, captured people that were forced into slavery. That is from just about any non biased historical source that any of us are free to explore.
Transportation of the slaves from West Africa across the Atlantic - which I think you are alluding to when you mention the link to 'our' relevance to slaving in the past - is a subject where you have to decide whether it is worthy of comment.
Concerning your second paragraph, I concur with every word you say and would hope that any sane and decent human being would agree.