The first graph above shows the actual ages of each patriarch when he fathered his heir. While the principle of increasingly late-life fatherhood is somewhat evident by looking at the ages graph, the perfectly consistent trend curve isn't apparent until examining the second graph, which shows each patriarch's age of fatherhood as a percentage in relation to his own total lifespan. In this way the principle of progressively delayed fatherhood is consistent both in relation to the individual's lifespan as well as their position relating to other patriarchs of their era. Potential inconsistencies such as Enoch's much shorter life, and the second era's progressively declining lifespan are thus factored out. Whereas Enoch was by no means as old in years as the other patriarchs of his era when he became a father, the percentage of his lifespan that passed before fatherhood occurred still shows the same increasing delay as the patriarchs before and after him.
God is amazing! He puts pattern, meaning, and consistency everywhere! Just like the order of the universe all the way down to the laws governing protons and neutrons, from His perspective He even makes sense and order out of what first appear to be simply random ages in the patriarchal lineage.
In passing down their oral traditions of the "begats" - could those ancient peoples have had any idea of the patterns and principles hidden in those ages of births and deaths, which only become apparent by graphing? For that matter, who even today has noticed these patterns?
I think few individuals enjoy charting and graphing God's patterns as much as I do. But, if you are one of those people, you should see the amazing patterns and relationships I could chart out for you between color and music! God has made the universe mysteriously and beautifully patterned and logical and interconnected. Nothing is random, everything is connected.