You are right DJ - I don't have any real knowledge of how Jewish scholars and theologians interpret the Torah and I bow to your superior knowledge on this however would you agree that the ancient Israelites had God's authority to subjugate other nations or not? Either they took captives or not.
It's not about the so called rights under the law of the time. It's not about retrospective interpretation of so called holy books. It's certainly not about some kind of relativism where this sort of stuff happened all the time in those days and those people enslaved by the Israelites were bloody lucky they'd not been captured by one of the other nations around them.
I am no Hebrew scholar but I don't need to be to know that type of slavery attested to in the Bible cannot be justified as some kind of pretend or pseudo slavery. People were forceably removed from their homes and made to work for others without any freedom of movement. It's wrong when it happens to women from Eastern Europe when they are forced into being sex slaves. It was wrong when it happened to Africans for 200 years. It was wrong when it happened to the Israelites and it was wrong when it happened to people captured by the Israelites.