Thanks for the comment. If I may quibble:

and at the time they had many slaves[...]

If memory serves, the Mosaic laws are said to be delivered to the Jews 90 days into their wandering in the desert after crossing the Red Sea. Which means that the people who received these rules about slavery were all recently freed former slaves. Unless they immediately started re-enslaving each other while wandering the desert with manna raining from heaven and water springing up from the rocks, I would think that none of them owned slaves.

[...]something that they wouldn't be willing to change. Instead of this, God commands how to treat these slaves.

That line of reasoning has never sat right with me.

God doesn't want people to kill. He knows people will do it anyway. He doesn't say "Make it quick and painless when you kill someone." He says "Thou shalt not kill."

God doesn't want people to steal. He knows people will do it anyway. He doesn't say "Only steal from people who are well off and can afford to lose some possessions." He says "Thou shalt not steal."

I cannot imagine the guy who tells people to cut some skin off the end of their penis has any problem with making big asks of people.