I'm just throwing this out there, I don't know how accurate it is but from what was shared and taking in what we have discussed on this forum for a while now, it appears that humans have hit a very long (relative) period of stagnation, at best(worst case de evolution).
Something happened. People moved underground. They stayed underground. They are still underground. All of a sudden some people get the idea to move up back to the surface. They see that some people survived what ever initially drove people underground.
The people sent from underground guided the survivors on the surface in certain directions, eventually what is essentially cult turf wars continued (it never ended). The people above ground are being guided to eliminate each other left and right until they no longer have the fire needed to fight any war or conflict. The surface people are now docile with increasing levels of sterility.
Fast forward to now. The people above ground are near boiling point. The people below ground, are still underground. Fucking and doing what ever they have been doing for so long. The people below ground have been surviving off the same tech that they brought with them after each 'happening'.
Where in all this is the improvement? Where is the growth? I don't see it anywhere but what I do see (from my limited perspective) is how the gods have been fighting each other through humans to decide the direction that humanity (mankind?) takes.
There is no growth. There is no new technology or things being created or done. Only a long, long war that is being fought with the technology salvaged from the last happening. . . that was salvaged from the last happening and so on and so forth.
Consistent decline. No growth. Purity diluting. Technology fading. Knowledge and information being burnt out of existence to only hold record in the genetics of the few that it remains (not taking the akashic into account) and even fewer who can access it.
I don't have the exact quote saved, but we discussed the time period in which 'Lord of the Rings' takes place. It was around 300,000 years ago, at least and if my memory serves me correctly this is also during the fourth age of man. This is the same time period that the OP in the information shared describes (up to now).
Ok, that's great but what of before then? Nick mentioned that the most his group is able to confirm humans have been around is 476,000 years. This is only a few more years than what is mentioned in the shared information and not that far off from when Lord of the Rings is said to have taken place (in the fourth age of man).
My point with this is to show that we 'know' and may even be certain that man has been around in some form or another for a very, very long time. What the few groups still around can only appear to confirm with certainty (with proof) is that we haven't been around longer than a little longer than the fourth age. Surely, there is more than that but as it was previously mentioned there are "swathes of millennia that are dark" and no one appears to know 'who' or 'what' is the force that is interfering with our collective ability to remember.
Who's records are still around that record such a time? Who's genetics would contain such information?