Why , Jesus’ blood?

Heb :10:4: For it is not possible that the blood of bulls and of goats should take away sins.
God tried to bring man back to him by making man sacrifice things that were dear to him, his prized unblemished animals, this only served as an excuse for man to continue in his evil ways, knowing he had another animal to give, if no other way, he could buy one. At most a temporary fix, no minds were changed, no hearts convinced, no repentance.
The sacrifice of our Lord Jesus Christ was not about him, it was about changing the heart and soul of mankind. The Father never doubted that his Son would do as he asked, he knew he would.

Heb :9:13: For if the blood of bulls and of goats, and the ashes of an heifer sprinkling the unclean, sanctifieth to the purifying of the flesh:
14: How much more shall the blood of Christ, who through the eternal Spirit offered himself without spot to God, purge your conscience from dead works to serve the living God?
15: And for this cause he is the mediator of the new testament, ----------------------- .
What can take away your sins ? Nothing but the blood of Jesus. A sacrifice so great that God would not let Abraham carry it through, a father giving his own son.

The only way sins can be done away with is the changing of a heart, repentance. The blood of animals just didn’t have that effect, on the human heart.

If the story of Jesus does not change a heart, I don't know what would.