I believe Gen 3 contains the answer. There’s so much in this one chapter! The point is that death is actually a blessing. We were meant to live forever by continued access to the Tree of Life. But when they ate from the tree God had commanded them not to eat from, the Tree of the Knowledge of Good and Evil (TKGE), everything changed. God had told them not to eat from the tree because he hadn’t created humans with the ability to handle that kind of knowledge and independence; instead, he had intended mankind to live dependent on him.
God knew that his Holy Spirit could not remain in man once they had eaten of the TKGE’s fruit, so warned them that on the very day they ate from it, they would die.
And sure enough they did die–not a physical death–but a spiritual death. Some of the effects were immediate: they realized they were naked and felt the need to hide from God.
According to Gen 3:22, had Adam and Eve been able to remain in the garden and eat from the Tree of Life, they would have lived forever, separated from God though. Therefore God removed them from the garden, and they inevitably died physically some time later.
Through Christ, God has provided us a means to have his Spirit restored within us. By abolishing the Law created when the TKGE’s fruit was eaten, and then raising him from the dead, providing for the restoration of his Spirit within us to those who believe and are immersed is his Spirit.