My honest hunch is that our human civilisation reboots every 5-6 thousand years of reaching a limit to all that we can achieve, earn or spend, after which we get psychologically depraved, devoid of each other we let jealousy creep in so deep that we destroy everything and nobody remains. How humans bury any evidence of whatever existed and restart the wheels of civilisation is a mystery. It was earlier thought that few individuals have been holding the keys to humanity’s rise and fall, but what I believe is that the algorithm which runs the network of people is so cold that it doesn’t care about whether anyone survives as long as people keep killing as predators or dying as masochists. It is only luck that with the help of other non terrestrial beings we are able to bring back civilisation from scratch. I fear humans as much as I fear aliens 👽, but they all keep each other alive even if they fight to the death for domination.