God required the price to remove his anger against the humankind who offended him. He wanted to see in that price a death, with bloodshed as evidence, demonstrating a sacrifice for the forgiveness of the sinners.
For God, all sinners had to die. So, when Jesus died, the corpse of Jesus represented the corpse of all sinners. God was satisfied when he saw the corpse of Jesus. God put in his mind that he had killed all mankind. The punishment was then given, and the problem between him and the humankind was resolved. Jesus Christ's corpse has ability to be the price required by God. His blood as a killed sacrifice is the evidence of the death required by God.
The blood of animals was not needed in the mankind's salvation process. The blood required by God was to be a mankind's blood. This blood had to come from the death of a perfect person, perfect as God himself.
The problem was only to be solved by the blood of God himself, because only God is perfect. But God could only die by taking human form, that is why the Second Person of the Trinity, Jesus Christ, descent to earth to die in the place of humankind, through an agonizing death at the cross of Golgotha, and therefore he paid the price required by God. Then, God died as self-substitution for men. He was God-man.
In beliefs of different world religions, we can't find any other god who died for people. Only God, in whom Christians believe in, died for humankind, and he had risen. He is alive. Only the Faith in God propitiated for sinners is True Faith, and other beliefs are false faith.
