Adam, made in the image of God, had eternal life until he sinned, the result of sin is death, Jesus, the second Adam obeyed God, died on the cross and restored eternal life to all those who accept Him as their savior.
I agree and would like to add more about Adam's fall.
Salvation for us today is directly related to what happened in the Garden of Eden.
Adam was told he could eat from every tree of the garden, but that he could not eat from the Tree of the Knowledge of Good and Evil, Genesis 2:17. So once Adam ate from the tree of the Knowledge of Good and Evil he had to be put out of the garden so that he would not eat from the Tree of Life and live forever, Genesis 3:22.
I don't know if people ever thought about what would have happened if Adam, who had already eaten from the the Tree of Knowledge of Good and Evil, had eaten from the tree of Life and lived forever. That would have presented a whole other set of problems for God. There would have been beings who were now tainted with evil who could live forever. Can you imagine what would have happened? Satan would have had new allies.
So God made sure that this would not happen and He put "Cherubims, and a flaming sword which turned every way, to keep the way of the tree of life," Genesis 3:24.
The reason man could eat from the Tree of Life and live forever is Adam's fleshly body could have change to a mortal body that would live forever based on the law of sowing and reaping - harvesting. 1 Corinthians 15 explains this process: Paul explains" ...that which thou soweth, is not quickened, except it die, 1 Corinthians 15:36. This process is just like planting a seed in the ground; the seed must die to become the body it intended. He explains that that which thou soweth, soweth not that body that shall be, but bare grain...., 1 Corinthians 15:37. And as we have born the image of the earthly, we shall also bear the image of the heavenly, 1 Corinthians 15:49. Paul explains a mystery though: "We shall not all sleep, but we shall all be changed, 1 Corinthians 15:51. This is the process in the Garden of Eden. Man being earthly, fleshly, if Adam had eaten from the Tree of Life, he would have been changed (without dying) to a body that would have lived forever. He would have gone from mortal (flesh) to immortal (spiritual/heavenly). Man has to have a fleshly body first before he can have a heavenly body. Like sowing and reaping.
So now, that process was halted: God's creation, fleshly man, who was created to live forever through the process of eating from the Tree of Life had fallen and headed for eternal damnation.
Now, what was God's plan to redeem man from his fallen state in order to accomplish is original plan for man? Jesus.
No man on earth could offer salvation to man, Acts 4:12. No animal that was sacrificed under the old testament law of animal sacrifice could offer salvation to man, Hebrews 10:4. So to redeem man, Jesus came in the likeness of sinful flesh, Romans 8:3. Jesus's sacrifice satisfied God to save man "that he not parish" due to the original fall, John 3:16.