You are like a looped recording. Either you plead that you have zero need to even begin to support the scientific premises actually used in all origin models, or you pretend you could, but somehow just won't. Oh, and then there is the ol 'I already said something important and offered evidence either in another forum, thread or etc etc, that you somehow cannot link to'.
I mean....seriously??!
Your basic question is why we can assume that there is some sort of uniformity in natural laws.
First, while it is a default assumption, it can be tested.
Suppose we have three events in the past and we want to know how long in the past they happened. Call those events E,F,and G. Suppose we have three different methods that *currently* give good results. Call those methods A, B, and C. They are based on different physical principles and work with different substances.
Your claim is that the laws of physics could have been different in the past and that would affect the results of all three methods. OK, that is a testable proposition.
Let's do all three methods A, B, and C to all three events E, F, and G. Since A, B, and C are based on very different physical properties, we would expect that changes to the physical laws would affect them differently. So, while it might well be coincidence that A, B, and C all give the same result for event E. It would be rather strange, under your assumption of different physical laws, for A, B, and C to *also* agree on events F and G. In fact, even the ordering of the events could be expected to be different if the physical laws governing the underlying processes were different.
But, we can go further. It is NOT just three events, but thousands. And it is not just three methods of getting (possible) ages, it is dozens. That there is any consistency at all is a strong case for regularity of the physical laws.
The only way out is for the physical laws to 'affect' each and every method by the exact same amount throughout all the events we have analyzed. But this gets into the very definition of what it means to measure time. If ALL physical processes are affected the same way, then *by definition* they all give the correct answers. We *define* time duration by those physical processes, after all.
So, we have considered your alternative (different physical laws in the past) and made predictions based on it (different effects on the different processes) and tested those predictions by observations *now* (inconsistent results across the different methods) and found your theory to be contradicted by the observations.
So, now, we have to look at *why* your proposal was considered valuable to you. Well, you point to human writings about people living to very old ages.
Which is MORE reliable? Writings from humans in the past, or physical evidence?
And the answer, clearly, is the physical evidence. Human writers *always* have a bias and, especially before modern times, the historical writings were meant as morality plays as opposed to accurate descriptions of events. The point of having people live to old ages was to say there was a golden age in the past and that we have declined from that point. It makes a good story.
But the physical evidence doesn't support the veracity of that story. And of the two, the physical evidence wins.