"So basically you're saying that instead of prohibiting slavery because he's the one who actually makes all the rules, God chose to let people own slaves because...they demanded it? Does he have to give in to their demands?"
I never said people demanded slaves. Authority came with the fall. Men running families came with the fall. And no, God doesn't have to give into people's demands, but He has granted people their dumb requests before.
My point is that God never banned kings even though He clearly was against the idea (just look at Manasseh to understand why), and the same would hold true for slavery. Matter of fact, Egyptian monarchs were abusing Israelites (to a degree I won't go into detail about to keep the site sfw) and God delivered them from it. American slavery was also abusive in a way I won't go into detail about.
This makes the whole Biblical slavery question irrelevant, but anyway I will mention that one time in the Old Testament someone got leprosy and their slave girl didn't want the master to die bc they treated her like family, and so she told them of a prophet, who eventually healed the master. Such treatment to slaves was extremely rare in America (I do know of instances where similar things happened, however because I read about history a lot).
God created us, so whether you or I agree with Him is really beside the point. However, He gave us rules and allows us to live comfortably on this earth, whether we hate His guts all day and night. Hate a slave master, king, or communist, and you're going to get hunted and tormented.
No, people who are pro-slavery are misunderstanding the Bible. It doesn't matter what people say; the Bible says what it says and means what it means. I've seen people try to use the Bible to promote hatred when the Bible says to love your enemies. Does that mean the Bible says what they're saying, or are they misusing the Bible?