One reason why archaeologists reject the idea of ancient advanced civilisations is the lack of tangible evidence, myths being considered not sufficient. Consider however that since the last glacial maximum roughly 20,000 BP, sea level has risen some 200 to 300 feet. Next consider that almost all major cities in the world currently are at less than this height above sea level; people like to live on the lower parts of rivers with flat land and near the sea for trade.
Next consider that as sea level rises, progressively higher land becomes the coast, which in bad weather is pounded by crashing waves. Where the sea invades land. such as on the East coast of Britain that is tipping down, almost nothing survives the battering of waves. The evidence for these very ancient civilisations is most likely under the sea, and all that will remain are the most massive constructions.
However those who comment on the possibility of advanced ancient civilisations, such as Graham Hancock and Chris Dunn, duck the issue of how it could have happened. We know in pretty fine detail the story of human development. Widespread agriculture did not develop until the neolithic and there is evidence in ice cores that large scale development of metallurgy did not happen in the hundred thousand years before our industrial revolution. The emissions that this caused are easily detectable in ice cores.
If you believe that metal machines were necessary to create the evidence of rock machining that we find around the world there are some inevitable conclusions. Though they may be hard to accept. The necessary metal was either created on earth in small-scale processes that did not emit the pollution we have found it necessary to emit. Or it was brought to earth from somewhere else. Both require science considerably beyond our current science.
The most economical explanation is that there was a relatively small group of people possessing advanced science and able to travel the world. That these people kept themselves separate from mankind except for a few favoured groups. They would have been seen by those who came into contact with them in pretty much the same way as the cargo cult islanders viewed the Europeans who visited their islands in ships and planes.
And the most economical explanation of where these people could have developed the necessary advanced science without polluting earth or leaving other evidence of sufficient mineral extraction is that they visited earth from another planet.
If that was the case they must have been able to thrive on this planet. We have evidence that DNA-based life forms can evolve technologically capable beings. And that the various varieties of these are sufficiently similar to be able to interbreed. We know of Homo Habilus, Erectus, Naledi, Floriensis, Denisova, Neanderthal and of course Sapiens. It is not too far a stretch of the imagination to imagine that DNA-based lifeforms developing on another planet similar to earth might produce a being pretty similar to Homo Sapiens.
The next bit of this logical sequence of deductions is to work out how recently they were here and when and why they left, died out or merged with our current population.