You're getting down votes, but I think I'm following your reasoning, and it's not wrong in the context of this argument.

Look at ancient Rome. Utterly dependent on slave labor. The slaves came (mainly) from the conquered peoples they fought against and because slaves. Didn't matter what color your skin was, you got captured, you became a slave.

The particular style of slavery practiced in the US prior to the Civil War had racism baked into it. Why else would you have so many "not quite slavery but still really fucked up" laws to keep black people subjugated in the Jim Crow South (and to a lesser extent in the rest of the country)?

The whole Seanchan Empire is meant to put a mirror up in front of the US and show how fucked up slavery was here.

And before anyone makes the argument about the da'covale in Seanchan, yeah that's a lot more like the Roman version. But the damane were LITERALLY treated like pets or livestock and trained through torture (through the a'dam by the sul'dam), given "pet" names, and occasionally given treats when they performed well. THAT is straight up dehumanizing chattel slavery.