Cultures around the world---from ancient Native American to ancient Middle Eastern to ancient South Asian ones---have some form of flood myth---a myth that involves the world flooding (obviously).
It is widely speculated that these could be related to the end of the last Ice Age: as glaciers melted, sea levels rose, causing coastal communities around the globe to get flooded.
Do you think every single flood myth (without exception) is based on the end of the last Ice Age/start of the Holocene Era?
Perhaps in memory of a tsunami caused by volcanic eruptions? Of course: Myths are not about historical happenings, they express eternal (semi)truths symbolically.