Jesus had to be a man, made in all things like unto his brethren. His brethren have sinful flesh and so must he have had.
Was Adam created sinful?
Jesus is called "the last Adam" because he was "sinless" like Adam was when God created him. Adam abused his free will and chose disobedience along with his wife, bringing sin into the world and physically passing on defective DNA to their children. (Romans 5:12; Romans 5:19)
Heb 2:16 For surely it is not the angels he helps, but the descendants of Abraham. 17
So h
e had to be made like h
is brothers in every way, that h
e might become a merciful and faithful high priest in service to God, in order to make atonement for the sins of the people.
When Jesus offered his sinless life it was so that God could condemn the sin in the flesh.
Jesus had no sin in his flesh any more that Adam did.
Rom 8 2 For in Christ Jesus the law of the Spirit of life has set you free from the law of sin and death. 3
For what the Law was powerless to do in that it was weakened by the flesh, God did by sending His own Son in the likeness of sinful man, as an offering for sin. He thus condemned sin in the flesh,
When the scripture says Jesus was without sin it does not mean his flesh was not sinful, it simply means he personally committed no sin.
The devil already had two 'scalps' on his belt.....he managed to tempt 2 perfect humans into disobeying their God, knowing full well that the death penalty applied. He tried the same tactic with Jesus. You seem to misunderstand that sin came from abusing free will, not because there was a defect in their physical structure. God did not created defective creatures.
"The tree of life" in the garden would have given mortals the opportunity to live forever. Being mortal doesn't mean you can't live forever, it just means that continued life was conditional. If humans abused their free will, then the death penalty would apply.
Everlasting life is not immortality....."mortal" simply means that you "can" die, not that you "must". Death is not mentioned in Eden except as a penalty for disobedience.
Sin introduced death.....a condition that resulted from sin. Jesus did not have that sinful condition. He chose to remain faithful under temptation....something Adam and his wife failed to do. It showed that they had no excuse for their disobedience and why God cannot forgive perfect beings, even angels for transgressing his laws.
Jesus' sacrifice ransoms faithful believers from the grave.
That is true, but they are not the only ones he died for. We have thousands of years where people did not have an opportunity to hear about God or to make choices about worship.God does not penalize people for sins committed in ignorance.
John 5:28-29
"Don’t be surprised by this, because the time is coming when all who are in their graves will hear his voice. Those who did good things will come out into the resurrection of life, and those who did wicked things into the resurrection of judgment. (CEB)
Acts 24:15 where the apostle Paul said.....
"The hope I have in God I also share with my accusers, that there will be a resurrection of both the righteous and the unrighteous." (CEB)
It is God's will that "all attain to repentance" so the resurrection is also for the "unrighteous" who died in ignorance, with an opportunity to bring their lives into harmony with God's requirements. At death, one is acquitted of sin.
Romans 5-7....
"For if we have been united with him in a death like his, we shall certainly be united with him in a resurrection like his. We know that our old self was crucified with him in order that the body of sin might be brought to nothing, so that we would no longer be enslaved to sin. For one who has died has been set free from sin." (ESV)
Paul is speaking on behalf of those who are chosen to rule with Christ in heaven. These will be 'kings and priests' and they will be 'resurrected first'. (Revelation 20:6) But not all who are Christ's followers will go to heaven. If they are 'kings and priests' then they need subjects to rule....and if they are to act as priests, then they will need sinners for whom to perform their priestly duties. Those who go to heaven leave their sinful flesh behind.
So who are these ones?
Jesus was not a substitute but a representative.
All the temporary blood sacrifices in Israel pointed forward to the permanent sacrifice of the blood of Christ.
He died instead of us.....so he was a substitute. (Galatians 3:13)