I always thought that Jesus had to come because of Adam and Eve.....am I wrong?
The Old covenant was one of Laws and rules and that didn't work very well did it?
There was also the issue of man doing horrid things and attributing it to God and using the fear of God to control each other ( I am a jealous God, a vengeful God, etc) and Jesus had to clear that up also.
Jesus saved us by his sacrifice, yes, but he also correct the OT view of what God is and what God wants ( A God of Love and forgiveness, Mercy not sacrifice, etc) and also to give a New Covenant based on Faith and Grace and a new commandment ( love one another, even your enemies).