https://en.wikipedia.org/wiki/Post-glacial_rebound
e.g. Here in Scotland you just have to look at a shoreline to see that relative sea levels have dropped quite a bit even though sea levels have risen. When I was a kid I can remember my father talking about legends of Vikings sailing round Roseisle in Moray - which is quite high and dry now.
"There is considerable discussion among archeologists as to the route taken by the first migrants to Australia, widely taken to be ancestors of the modern Aborigines. Migration took place during the closing stages of the Pleistocene, when sea levels were much lower than they are today."[1]
"It is generally believed that Aboriginal people are the descendants of a single migration into the continent, a people that split from the first modern human populations to leave Africa 64,000 to 75,000 years ago, although a minority propose that there were three waves of migration, most likely island hopping by boat during periods of low sea levels"[2]
[1]: https://en.wikipedia.org/wiki/Prehistory_of_Australia#Arriva... [2]: https://en.wikipedia.org/wiki/Indigenous_Australians#Arrival...
Maybe the sense of wonderment in finding new grounds is not enough to be folk-told throughout generations. As in the news, we tend to stick to the bad news rather than the good ones.