Fam the only reason race was around was to justify treating a people as subhuman, that's the only thing it rectified. All those cultures wanted to be involved in the money making slave trade so they all subscribed that theory.. that gave them common ground.
I agree that it was used to demean but it's also easier to process on an implicit level. This can be shown in any lab test, the amount it would take the brain to activate and process color vs the multi-level processing needed to distinguish culture.