I’m just referring to the Biblical account of these events. The environmental differences required to live 900-1000 years would be interesting to understand. If there was a significantly lower amount of c-14 5000 years ago what would the affect on carbon dating be? I assume we’d all agree the environment to support a lifespan in humans to be 1000 years old would be different then the environment we live in today.
The Bible is not a science textbook. People never lived many centuries. There are several possibilities for why these numbers are listed the way that they are.
In the Sumerian kings list, neighboring ancient Israel, kinds were listed to have lived for 10s of thousands of years. But these ages were used moreso in ways to highlight the significance of the figures being described. It wasn't so much a matter of actual natural ages of people.
Enoch lives the same number of years as there are days in a year for example. It's not really a natural age. It has a figurative component. Or another example is lamech:
Genesis 4:24 NRSV
[24] If Cain is avenged sevenfold, truly Lamech seventy-sevenfold.”
Genesis 5:31 NRSV
[31] Thus all the days of Lamech were seven hundred seventy-seven years; and he died.
The Hebrew word for the number "7" has the same consonants as the word for "completion". This number is used figuratively, several hundred times in scripture. So when lamech lives to be 777 tripartite 7s, with prior reference to lamech being avenged 77 fold and Cain 7 fold.
These are figurative expressions. It's not about biology.
In fact, if you look closely, all the ages of the patriarchs end with the same numbers.
Genesis 5:5, 8, 11, 14, 17, 20, 23 NRSV
[5] Thus all the days that Adam lived were nine hundred thirty years; and he died.
[8] Thus all the days of Seth were nine hundred twelve years; and he died.
[11] Thus all the days of Enosh were nine hundred five years; and he died.
[14] Thus all the days of Kenan were nine hundred and ten years; and he died.
[17] Thus all the days of Mahalalel were eight hundred ninety-five years; and he died.
[20] Thus all the days of Jared were nine hundred sixty-two years; and he died.
[23] Thus all the days of Enoch were three hundred sixty-five years.
930
912 (-7 is 905)
905
910
895
962 (-7 is 155)
365
All of these numbers, and I could keep going, but they're all divisible by 5, or divisible by 5 with the addition or subtraction of 7 (the number of completion). Which, are numbers that aren't realistic.
And the days that these people have children are the same.
Adam has Seth at 130.
Seth has Enoch at 105
Enosh has kenan at 90
Kenan has mehalalel at 70.
Mehalalel had Jared at 65.
Jared had Enoch at 162 (-7 is 155)
Enoch had methusaleh at 65 etc.
As if the patriarchs intentionally waited until their ages were divisible by 5 before having babies.
It's just not realistic or natural.
Given the Sumerian kings list which does the same thing, culturally, these are figurative. It's just how ancient people presented their kings.