Excellent summation of our possible history. I agree.The thing about those old maps brings to me the question so often asked about so many things that were made in ancient times that don't make sense based on what we think that we know about their available technology. My personal belief is that at one time, or maybe many times, in the past mankind rose to great heights only to be slammed down by any of dozens of possible natural cataclysms.
There are many indications that this planet has regularly been hit by work wide disasters. The layer of iridium at the KT boundary marked the end of the dinosaurs. There is a line of charcoal that is worldwide that indicates that 12 to 15 thousand years ago the world experienced a worldwide conflagration probably from a truly MASSIVE solar flare.
there are also indications that there was some sort of flood with worldwide effects. This could have been the result of an asteroid strike in the deep ocean or possibly a sudden shifting of the crust. The shifting crust would explain the fact that at one time Antarctica was a very warm and wet place with huge forests that left huge coal deposits.
The thing that I realized one day is that mankind seems to have a sort of growth pattern like most living things. We start slow and slowly grow in population and numbers and then suddenly skyrocket to new heights in both population and technological level. In 1920 the world population was 1.8 billion. In 2020 our population is 7.8 billion. In 1920 we were plowing our fields with animals. We were just starting to fly. We were steam power and in the early days of the internal combustion engines. Most people warmed their homes with fire from wood and coal. Medicine was barely above the level of healers and had no antibiotics. One hundred years later we have been to the moon and are talking about going to Mars. Technology has exploded in all possible directions. ONE HUNDRED YEARS!!! How many times could we have done this in one hundred thousand years?
If we were t be wiped out again we would fall all the way back. One of the things about our high technology that very few people actually grasp or could duplicate most of that technology. Most people now don't even know how to feed themselves other than going to a store. We couldn't fall back to animal-powered farming. The animals don't exist in the kinds of numbers we would need. Nobody knows how to make the harnesses. we would fall back to a hand to mouth human-powered level.
Modern man doesn't build with huge stones. We use other far less durable things to build hour cities. Were we to be knocked back in a thousand years there would be far less sign of us than the Egyptians, Romans, and Greek. They were an early part of our line. there are indications of other lines that existed in the far past. the higher levels of those lines left little impression so all we have are hints of their early stages. Over and over man has gone through the stone age in their rise to great heights only to fall and their heights vanish leaving only the works of their early ancestors left to puzzle people next time we rise up and search for answers.