He is overturning it, it called for equivalent harm and now He calls for complete forgiveness. I don't see any scenario where the proposition that Jesus confirms the national law as maintained is true when He is literally and explicitly changing it. You will have to draw that proposition out such that the result of Jesus's statements are exactly the same as the law. That plainly can't be achieved.
So, the whole "eye for an eye" concept calls for the death of murderers. They took a life, so their life is taken. You're saying Jesus overturned this by calling for complete forgiveness? Or should we say that we can only assume that any changes He called for only apply to the specific things He mentioned. All it takes to "condone" something is to say nothing about it.
They don't own the people in the sense you imagine, they still have certain rights. They do however give up certain rights voluntarily. Anything can be abused. What is interesting is that it was their unfaithfulness to God that led to such abuses. Your comment about attacking other cities is far off the topic of slavery. We can talk about that but I'd prefer to finish our current topic to your satisfaction. If we complete this topic and you do decide that you want to talk about it I need to know a bit more about what you are referring too.
I already said that indentured servitude isn't inherently immoral. Time to move on to slavery. Those cities that are "at a distance" are not off topic. That's part of the real slavery in the Bible. The cities near to them within their promised land would be off topic, because then we would only be talking about genocide. Those aren't the cities I'm talking about though.
When you draw near to a city to fight against it, offer terms of peace to it. And if it responds to you peaceably and it opens to you, then all the people who are found in it shall do forced labor for you and shall serve you. But if it makes no peace with you, but makes war against you, then you shall besiege it. And when the LORD your God gives it into your hand, you shall put all its males to the sword, but the women and the little ones, the livestock, and everything else in the city, all its spoil, you shall take as plunder for yourselves. And you shall enjoy the spoil of your enemies, which the LORD your God has given you. Thus you shall do to all the cities that are very far from you, which are not cities of the nations here. -- Deuteronomy 20:10-15
That is slavery, and that is the topic.
You say owning people is bad because your moral intuition about men being free is compelling you. However infringing on ones right to be a servant is a restriction on that persons free will which would leave that person stuck in poverty. Your moral intuition is right to see the freedom of mankind as the proper course but it's being inappropriately applied. Where do you suppose your moral compass points to?
If someone wants to be a servant, have at it. They should always have the right to change their mind though (
not necessarily without any consequences whatsoever), and they shouldn't be forced to be a servant. The "owner" in this scenario is the immoral one who offers no choice to the "servant" other than enslavement to alleviate their poverty.