Those are fair philosophical questions.
The problem was the slaves were black; they stood out; if you were a free black, people would probably still have assumed you were a slave. The association lingers. They still stand out. Other ethnicities blend in over time. Blacks never do. They’re still black. Society/government have tried to resolve this, but apparently it can’t.
I apologize for the first stupid remark, I suppose I thought I was being clever.