He died before his time
Genesis 5: Adam lived a total of 930 years. And he died.
I’ve heard that the very long lives of people mentioned in the first pages of Genesis are the result of someone’s counting the seasons as years or something like that. While I have no authority to say it, I’ll say it anyway: I think that’s silly. Based on the Creation story, I think the Lord designed human beings to live forever. It’s their disobedience that brings death into the world. In fact, this very moment the only man already possessing a resurrection body is still alive 2000 years down the road. He’s physically at the right hand of his Father right now. Sin short-circuited the “forever aspect” of human life and it’s Jesus who redeems, not just the souls of people, but our bodies as well. At this point, Jesus is the only man to experience the redeemed body, but judging from his post-resurrection appearances the new body is a fascinating mix of familiar (eating) and unfamiliar (appearing and disappearing). Now, back to Adam. I think his extremely long life is a residue of his original design. If you think about it, his body was designed for eternity and he “only” lived 930 years. Soon, God will move to further limit life spans, not once, but twice. The original limitation, though, is the big one. Because of sin, life expectancy is throttled back from forever to under 1000 years. For a creature intended to live forever that’s like dying in infancy.
Take away: Jesus redeems us entirely, body and spirit.