OP clearly says Father offering son as a sacrifice (both of Abraham and of God) is a human thought, written by humans. That means God is nowhere in the picture, says the Bible. (Luke 6:38)
I don't buy that it was. God, in my view, was very much in the picture. Abraham was commanded to sacrifice his only son as a type and shadow of the Father having to offer his Son, and I believe Abraham was acutely aware of that. He had a deep and abiding relationship with God; he knew that God was very much against human sacrifice, and he trusted God as a being of integrity and honor. Thus, he had every reason to expect that Issac would be spared. Some ancient accounts go so far as to say that if God did require Isaac to die that God would restore his life, but most seem to support the idea that God would somehow stop the sacrifice, which he did.
Why try to read anything else into it? Many Christian scholars have written about this extensively and they come to similar conclusions. Abraham learned of Christ by and through the commandment of God that came to him---that he should sacrifice Isaac; otherwise, the story makes little sense. If this story is marginalized, then Christianity makes little sense. But together, the religion of Jesus works masterfully as it looks both ways through the corridors of time.
At least that's how I see it. (I'm unsure of exactly what you mean by your allusion to Luke 6:38.)