Why did the sacrifice of animals in the Old Testament only temporarily cover sin for people (if it was an innocent substitute), while the blood of Jesus covers us entirely from sin? I’m not trying to or intending to compare Jesus’s blood with an animal’s blood, but why was the shedding of an Innocent Man’s blood worth so much more (in God’s eyes) than the shedding of innocent animals blood? Was it because only God Himself was able to pay for the sins of the world on the cross?
God’s law requires that unless a person can redeem themself, only a kinsman can redeem what he has lost (Leviticus 25:25-26). This is why God had to become human. No one else could redeem us. We are unable to redeem ourselves because of our own sins. No person can redeem anyone else for the same reason. An angel could not redeem us because angels are not kinsmen.
God knew that He could redeem us, but only by becoming a human Himself. Otherwise, He’d be breaking His own laws. Since He was only going to do this once, He allowed the blood of innocent animals to set aside the penalty until He came to die for us, but only if the person understood that the animal was a temporary stand-in for God. Hebrews 10:1-18 explains this.