Deep down you know you're wrong. This is typical behavior on your part.
I find this to be completely disengenuous. He'll tell you what he thinks and you will simply claim the bible doesn't say that with no justification.
One can't own another meat machine? Why?
I'm not sure why he would waste his time giving you answers when you summarily dismiss them as "mental gymnastics". Here is the short answer.
God didn't "change His mind", God told a specific people to do specific things for specific reasons.
Oh it doesn't bother me. The bible is fairly easy to understand. At least the generally speaking. There is quite a lot I still don't know but things like this keep me thinking. Mostly people quote the OT and forget about the NT when they are trying to make God look bad. It confused me for a while to as why God seemed to be a Jekyll and Hyde persona between these two covenants. But one thing that I found interesting in the OT is that Satan is only mentioned 3 different times. The garden of Eden, Saul seeming out a witch, and in job. Everything else that was good or evil was attributed to God. And in the KJV it makes it seem that God is out to get you. But I was listening to a scholar who studied the original language and said that in the OT we see phrases like God will smite you with sickness when the actual rendering should be understood that He will allow this to happen to you. Now pair this up with the NT where Jesus is presenting a Father who loves you, and Satan who wants to destroy you and sin that allows evil to happen to you and it becomes a lot clearer how the Bible fits together. The Bible teaches that we are free to make our own choices and it lays out the results.
Many of the laws you read were more cultural than anything else, but that makes sense as the OT was basically a historical document of Israel.
But many of the laws were far more lenient and fare than any other country of that time. Slavery did occur but it wasn't because you were racist but the legal system allowed you to own people. It also protected the slaves. In numbers it talks about if you beat a slave you must let him be free. Then we have the year of jubilee where anyone who was a slave do to owing debt etc was to be made free and have their debt cancelled.
There's just so much more in the Bible than just do's and donts. Jesus summed up the OT law when the Pharisees questioned him on the matter by saying "love God is the greatest commandment and love your neighbor is the second most important". Again Jesus tackles an issue when the Pharisees bring a woman caught in the act of adultery and the law says she should be stoned. They ask Jesus what should be done and He replies whoever is free from sin can stone throw the first stone.
People forget about the mercy and forgiveness and just focus on the law. But just like the court system we have here in the states the law states the maximum punishment but that doesn't mean the courts never give mercy.
Well I just wrote that up quickly so hopefully that makes sense.