Good to see you write in terms of likelihood. A shorter length of time given for human observation throughout history only means less knowledge upon which to build. The stock in trade of science is human knowledge. All hypotheses, experimentation, and recording of results must take place by way of human intelligence. If a human observer was not present in time 4.5 billion years ago, then the proposition that the earth is 4.5 billion years old must be treated as reasonable conjecture. Nothing more, and nothing less.
As for a 969 year-old human observer, I take it by faith that the biblical proposition is true. However I am disinclined to think the Gregorian calendar was in use when these words were first spoken. The biblical account reads with considerable detail where human generations are denoted, and for good reason. Until the creation could be set aright through God's intervention in human flesh, it was necessary that the line of human flesh through whom the Creator would intervene be documented.
No, it could be treated as a good theory strongly substatiated by evidence.
As for a 969 year-old human observer, I take it by faith that the biblical proposition is true. However I am disinclined to think the Gregorian calendar was in use when these words were first spoken.
Unlikely the difference between the Julian and Gregorian calendars made much difference to Methuselah's age. Unless you mean we had a 50 day year back then. That would be impossible too.