Yes, in Confederate states, anyone who was Black was by law automatically a slave *unless* that slave had been officially freed by his/her master…and even then they didn’t have freedom of travel, for if they traveled, they might be accused of having false papers. It was a matter of race. And for anyone who tries to dispute whether the Civil War itself was over slavery, please read the first paragraph of the Mississippi Articles of Secession.
And in the days of Jim Crow, well, your quote by Thompson shows that it wasn’t a matter of which Black, but all Blacks (it actually extended to anyone who wasn’t White).
Your statement “ The western world has to decide whether it will be inclusive or it will risk multi-cultural identity politics leading to disaster” is very much like something I’ve said for years: we can have freedom from discrimination or we can have freedom to discriminate; we can’t have both. That being said, in my experience in Asia, racism is much more accepted and expected, and when they immigrate to America, some are rather shocked as to how much racism is a part of our national discourse.