Strangely, the Bible does not repudiate slavery. Heck, the left may be going after that next. Uh....... never mind.
You are quite right about the Bible, sadly. Throughout slavery is just accepted as a fact of life, neither good nor evil in itself.
However, I do think the notion that it’s evil grew out of biblical concepts. After all, if we’re all equally children of God how can some of us own others as chattel?
Western Civ, based on the Bible and classical civilization, was the first civilization in history to reject the idea of slavery and develop notions of inherent human rights. Never crossed the mind of any other civilization.