There are one of three theories, as I explained.
1) A genetic memory of evolution to life on land. Remember this? Remember the threead is supposed to be evolution? Instead, you guys ignored this and this is why the thread might be closed. Because we cannot agree on any part of the premise. Now I don't know when this happened, but you're focusing on the idea of a worldwide flood and not the actuality of evolution. "Sure, fine, genetic memories are a thing, let's move on." This is what you say if you want there not to be an argument, you accept parts of the premise and keep focus on evolution.
2) You're confusing a sudden worldwide total flood with a worldwide lowest points flood. In other words, you're creating a strawman. This is another way to create heated debate that closes threads.
But what I actually said was that water level rose after the ice melted from the last Ice Age. It was significantly less than I thought, but it was exactly the areas that had flood myths. For example, China has a flood myth, but Japan doesn't. This because those in the area between China and Japan that flooded immigrated to China. You're also thinking of this as a single fast flood. This is actually like the erosion that is happening to many coastlines in America. Tangier Island, parts of New Jersey, parts of Florida, these areas sink or erode. For other areas, swamps fill in or volcanoes erupt, and land is added. Likewise, people are always talking about climate change or whatever. If warmining happens, the areas flood (that is to say, over the course of centuries water table becomes higher). This isn't "didn't happen" it very much did happen, and no there are many many cultures it happened to, not just the Bible. You can clearly see the difference between today's landforms and this projection map, and it is known that the so called Native Americans crossed through Russia while that area was land. The "flood" happened. Deal with it. In fact, if climate alarmists are right, it is still happening to areas that are washing away. Btw, from that map, you can see where land used to be at some even earlier date.
3) My last explanation of this, had little to do with actual flood and more to do with how legends get passed down. In addition to flood stories, Earth has stories of otherworldly immigrants. Selkies, the legend of Sakuya, Ezekiel's Wheel, and stories of angels. This is what's tied to the whole Phaeton thing. Planet blew up, and humans came from there. Or some humans came from there and mixed with the rest.
You're fixating on some guy named Noah, and being far more of a literalist than I, in some attempt to create a strawman. But the more you do that, and the less you listen, the more likely this thread closes. So listen up. There are three reasons, none of which imply "worldwide flood" to the point where the whole map looks like water. But I never said that.