This is a well known trend in the scriptural accounts of antiquity.
Job was one of those long-lived humans.
Some (notably, Hugh Ross with his OEC) have speculated that nuclear radiation made the difference, such as the Vela supernova... maybe. I’ve gotten leery of “scientism” both in old earth and young earth flavors, when we are dealing with a God that can keep Israelites’ shoes from wearing out during 40 years of wandering.
Gerald L. Schroeder the Orthodox Jewish physicist, author, does an excellent job of explaining Biblical time - his “Science of God, The Convergence of Scientific and Biblical Wisdom”, “The Big Bang” takes nothing away from the Bible while giving the reader a broader view. All of his books are enlightening, his “Hidden Face of God” is truly a gem.
Those who study aging are convinced that age is just the process a body goes through as it breaks down. You slow down the break,down, you slow down aging. In theory, they believe aging could eventually be stopped altogether through rehabilitative, nutritional, and preventative methods.