You don't understand what that Tanakh is when it comes to the Jewish faith. The tanakh is the story of a people's search for God, and an example of how even people who are flawed can find sanctity in God. It also is some rules to follow to help bring people closer to god.
One of those rules is 'NO HUMAN SACRIFICE'. This was demonstrated by Abraham, when the ram was provided instead of Issac. That was considered a promise from god never to require a human sacrifice ever again. That makes the concept of "Jesus was a sacrifice for our sins" against what the Jewish faith believes about God.
It's not a free gift if you have to give up everything you believe in to accept it.