How are we apart of the Covenant that God made with his people in the Old testament

We are all apart o the covenant of God if we know it or not. There are many parables in the bible. this one is the story about adam and eve. God said to the serpent<< We will crush your head but you will bight back>> What God is really saying is that he will send a Savior. That savior is Jesus.Even though we are not Israelites  God sent the savior for everyone including the people who were not even alive yet(That would be us). He saved us from our sins, he changed us, he made us new.