Jesus became a sin offering, He never became a sinner.
Jesus was the first born from the dead
Colossians 1:18
And he is the head of the body, the church: who is the beginning, the firstborn from the dead; that in all things he might have the preeminence.
He was separated from God on the Cross in our behalf. We know this is true because Jesus said "My God, my God, why hast thou forsaken me" (Matthew 27:46) He was separated from God as a sin offering for our sin because the wages of sin is death which is separation from God (Romans 6:23)
Most people don't realize that the first man to get born again was Adam. Only, Adam got born again from life to death in that he was in union with God, he sinned, and became separated from God because of sin and died spiritually.
Jesus on the other hand never did any sin Himself, but he was made a sin offering for the sins of mankind and God forsook Him in our behalf - and then Jesus was raised from the dead and become the first man to be born again from death to life.
This why the Word of God says Jesus is the firstborn from the dead.