IMHO just because there are flood myths around the world does not neccessarily mean that the "Great Flood" happened round the world at the same time. Is it possible that floods and tsunamis have occurred throughout history and around the globe, so that different civilizations created "flood" stories? Is it possible that early civilizations created "flood stories" to explain finding sea fossils around the globe and at higher elevations that were caused by geologic activity? Is it possible that flood and tsunamis occurred and that early civilizations created stories of a "Great Flood" to explain uncovered sea fossil remains after flood waters receded?
My point is that many civilizations having "flood myths" does not prove that the "Great Flood" occurred. It is unlikely that the "Great Flood" occurred around the world at the same time about 13,000 years ago because insufficient time would have lapsed between then and now to account for the diversity of modern humans. If it happened more than 1 million years ago, then I could not use the same justification to conclude that the "Great Flood" did not occur. According to Timeline of human evolution, (Archaic) Homo sapiens have been around for about 500,000 years.
Peace be with you and everyone, who you love,
Robert