The Jews who rejected Jesus did not recognize Jesus' words as being the words of God.
Jesus did teach atonement. God gave the teaching tool and shadow of Jesus to Moses to give to the Jews.
Even John the baptizer, the forerunner, the one who prepared the way for Jesus exclaimed that Jesus is the Lamb of God who takes away the sins of the world.
The blood is for atonement. There is no forgiveness of sins without the shedding of blood.
Leviticus 17:11 For the life of a creature is in the blood, and I have given it to you to make atonement for yourselves on the altar; it is the blood that makes atonement for one's life.
Hebrews 9:22 In fact, the law requires that nearly everything be cleansed with blood, and without the shedding of blood there is no forgiveness.
John 1:29 The next day John saw Jesus coming toward him and said, "Look, the Lamb of God, who takes away the sin of the world!
The Jews had adopted Pagan sacrifices for sins, Jesus taught repentance, a change of heart, forgiveness and salvation by faith, all of which takes away the sin of the world. The original gospel changed after Jesus left, it was modified for the simple minded people of the Pagan world. The Romans already believed in blood drinking and blood sacrifice, so they were more receptive to Pauls remixed version.