It gets weird though when you realize cultures from eastern Asia and South America also had flood narratives.
Watch the TV news. In the last few weeks there have been floods in Australia, India, the US, South America, Europe, China…There are floods everywhere all the time. So why is it weird to think that floods were everywhere in ancient times?
But as several people have pointed out, there is no need to take the story of the Flood literally. The point of the story is that mankind had sinned and would be punished, but that God was merciful and promised not to do that again (rainbow as a sign…but don’t take that literally either!). Whether or not there was a flood, local, regional, or worldwide, is irrelevant to the point of the story. There are also stories in the Bible about fire and brimstone (Sodom and Gomorrah), the fires of Hell, etc. If you want to take all these stories as literal truth, good for you, but as a Catholic that’s not necessary.
Water as some sort of cleansing fluid is a common theme, not only in the OT, but in most cultures. For example, Mongols thought running water was “pure” no matter what, Hindus think the Ganges has special properties, etc. So the Flood as some symbolic precursor to baptism is a logical assumption.
A simultaneous world-wide flood is simply anti-scientific. Yes, sea levels have risen about 660 feet in the last 12,000 years, but that didn’t flood the land that exists today.
If you are really keen on the literal truth of a regional flood, certainly the Tigris and Euphrates (where the Jews lived…Abraham was supposedly from Ur) flooded all the time. If you prefer another theory, as sea levels rose in the last 12,000 years, what had been land in S. Mesopotamia slowly became the Persian Gulf. Certainly the population at the time would have kept the folk memory of that alive.