There are different forms of slavery. The US was unique in that it was a system of race based chattel slavery, and really, the idea of “race” was invented alongside it.

Slavery in west Africa would often mean that the person would end up being integrated into the tribe over a long period of time (varies immensely group by group, but still the general trend). In the Middle East, Muslims were not allowed to hold other Muslims as slaves, so sometimes conversion could be a ticket out (there’s some funny complexities there).

Slavery in the US was a uniquely barbarous institution. It was industrialized, it treated people as resources. Perhaps an especially brutal Roman latifunda could compare in an individual’s experience, but even then, a freeman in Roman society would still be about equivalent to most every one else.

Slavery didn’t stop in the US after it ended. Tons of masters chose not to tell their slaves that the Emancipation Proclamation had freed them until sometimes decades after the fact. After the Civil War, the KKK ran a campaign to terrorize Black communities. Communities also immediately passed things like vagrancy laws, which started the system of slavery as punishment for a crime that we still have today.

There have been forces in the US attempting to minimize slavery since before the ink was even dry on the peace treaty. Please do not join them.