Your other statements:
He [God] declared that the soul that sins shall die
The sinning soul will die.(Eze 18:20; Eze 18:4 ). Amen.
He also declared that without the shedding of blood, there is no remission of sin.
Is there an OT reference to that?
His mercy is keeping us all alive, but he offers eternal life to those who will believe.
Then the Gift is not free.
I had thought the verse was in the Old Testament
Not a chance.
but it is in Hebrews 9:22, "and without shedding of blood there is no remission."
How appropriate for this season, but its not in the Law. The Torah says nothing of atonement for future generations.
Jews have a day set aside once a year to atone for their sins, for all generations And this shall be an everlasting statute unto you, to make an atonement for the children of Israel for all their sins once a year.
You may not know this, but the Passover lamb is meant to be eaten (Exo 12:3-10), the sacrificed animal may not be human, neither is eating flesh nor drinking blood allowed in Judaism.
Passover is a commemorative event. One does not atone for sin during Passover.
Sin sacrifice is defined in Leviticus 4. The sacrificial animal must be an animal approved by God (humans are not), must be physically unblemished, must be done by a Levite priest, death must be due to blood loss (not suffocation), at an officially designated area (not an execution ground), the blood is poured or sprinkled on the altar.
Leviticus (22:20,24) specifically makes clear that the animal must be physically perfect and that nothing that is bruised or crushed, or broken or cut will be acceptable.
The animal used on the Day of Atonement (Lev. 16:5-34), is not killed. The animal for that ritual of atonement of sins is a goat, a scapegoat, upon whose head are symbolically placed the sins of the world; obviously the animal of the atonement in the Law is a goat not a lamb.
That is why Jesus said he came to fulfill the Law, not only by obeying the Law perfectly, but he also became the fulfilling sacrifice which the others were a shadow of.
Some Hebrew sacrifices did involve animal blood. (Lev 17:11) However, if that is true, than it should also be true that we are not allowed to drink blood (Lev. 17:10), lest it not be forgotten that even the symbolic sin is a sin (Matthew 5:28).
Going by the Law, it will also be true that one can only atone for ones own sins The righteous shall be credited his own righteousness, and the sinful shall have his own sin counted against him. (Eze )
Moses tried to atone for the sins of his people, and God refused saying that he will only blot out those who have sinned against Him.