You're looking from the end backwards, instead of from the beginning forwards. 5000 years ago, did Noah think black people were human? Did the Egyptians? Did the Greeks? The Romans? Did any Christian Europeans think they were humans?

Then one day, we start thinking they are humans, so you say "well I don't want to offend God."

Then the next question is, what is a human? I don't mistreat my dogs and they aren't human. I don't think blacks should be slaves. I'm not saying we should hurt them. But they just aren't the same as us. There is no common ancestry.