This whole thing really confused the Jews too. The thing was, the law was added to teach us and point to Christ.
We were told the life was in the blood, this wan’t a biology textbook, it was pointing forward to something.
And that while God gave us the animals for food and such, life belonged to God. So you honored the order of things by giving the blood, the life to God.
And we know that no sin was forgiven without blood, without life, but we also know that no animal sacrifice ever paid for anyone’s sin.
Everything pointed towards Christ and his sacrifice. And the teaching still continues.
Where is the life? It is in the blood. What paid for our sins? The blood of Christ. What is the wine in the Lord’s Supper? The blood, Christ’s blood of the New Covenant given for the remission of sins.
So to this day, the life is in the blood. It belongs to God, and he gives us life through it.
We don’t turn back to the Old Covenant because it has been fulfilled, fulfilled in Christ. To turn back is to doubt the New.