Wrong, it was God's fault. He forgot to include slavery in the prohibitions enumerated in the Ten Commandments and the Noahide Laws.
If God screws up, what are we supposed to do about it?
What is slavery besides theft of another’s work, and coveting his work in the future?
Well there is the rape of the women and the torture or murder of any who resist.
I figure the 10 commandments have it pretty well covered.