You list several instances where bodies or even parts of bodies were used as payment, literally or metaphorically.
Well, what is the Eucharist, for heaven's sake? It's a payoff on a hundred levels. It's paying off God, because God is vengeful. The incarnation and crucifixion and sacrifice of Christ is the law of the talion. You owe a god to a god for a breach of god's rights.
Not only that, but God has to divide himself into more than one person in order to pay himself off. But it's paid on behalf of mankind, who could never pay back what's really owed.
It can't be God just paying God. Christ is also the perfect man, a man who is God and then pays God. So the balance is exactly right, an eye for an eye. Otherwise, God is undercompensated.
But the original 'eye' in this case is the disobedience of eating the apple in the garden, and the life of a god seems like a high price to pay for that.
Well, God was never what we would call a proportionalist. God goes postal a lot, which is what human societies won't let their people do.
So, in a way, the Old Testament God is exactly the kind of vengeful berserker that modern justice systems promise to protect us from.
And it goes on. Really, I never understood the savior thing, even in my pre-agnostic high school days, but I couldn't put my finger on what was wrong with it until I read a parody (that may not be at that site in particular) of a Chick tract that put it something like this: "Why would I need to sacrifice Myself to Myself, in order to make Myself change a rule that I made up in the first place?"