The Extinction Event

Because God repented that He had made man (but that idea is not shared with all other flood stories).

Right. And according to the story, who survived the Flood?

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We can allow satellites, planets, suns, universe, nay whole systems of universes, to be governed by laws, but the smallest insect, we wish to be created at once by special act.

-- Charles Darwin

We both know the story. Go ahead and say what you intend to say.

I'm just trying to make sure we're on the same page.
The Bible claims that all of humanity was wiped out, except for Noah, his wife, the kids and their respective wives. That means that almost 100% of humans was wiped out in the (supposed) global flood event.
So if we're going to try to account for Noah's Flood by one of the mass extinction event horizons we see in the fossil record, then there had better be some human fossils in the mix. But there aren't. The first humans are found way up at the top of the rock record, as I said, long after the last mass extinction is recorded at the K-T boundary (between the Cretaceous and Tertiary in the image below):



The other four mass extinction horizons are at the end of the Ordovician, Late Devonian, end of the Permian, and end of the Triassic. We don't find any human fossils anywhere within those extinction horizons or in between them. Thus, it makes no sense to conclude that Noah's Flood is recorded anywhere in those event horizons.

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We can allow satellites, planets, suns, universe, nay whole systems of universes, to be governed by laws, but the smallest insect, we wish to be created at once by special act.

-- Charles Darwin

In biology and ecology, extinction is the death of every member of a species or group of taxa. The moment of extinction is generally considered to be the death of the last individual of that species (although the capacity to breed and recover may have been lost before this point). Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "re-appears" (typically in the fossil record) after a period of apparent absence.

Through evolution, new species arise through the process of speciation—where new varieties of organisms arise and thrive when they are able to find and exploit an ecological niche—and species become extinct when they are no longer able to survive in changing conditions or against superior competition. A typical species becomes extinct within 10 million years of its first appearance, although some species, called living fossils, survive virtually unchanged for hundreds of millions of years. Extinction, though, is usually a natural phenomenon; it is estimated that 99.9% of all species that have ever lived are now extinct.

Prior to the dispersion of humans across the earth, extinction generally occurred at a continuous low rate, mass extinctions being relatively rare events. Starting approximately 100,000 years ago, and coinciding with an increase in the numbers and range of humans, species extinctions have increased to a rate unprecedented since the Cretaceous–Tertiary extinction event. This is known as the Holocene extinction event and is at least the sixth such extinction event. Some experts have estimated that up to half of presently existing species may become extinct by 2100.

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What would we do without you, Sphinx777?

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We can allow satellites, planets, suns, universe, nay whole systems of universes, to be governed by laws, but the smallest insect, we wish to be created at once by special act.

-- Charles Darwin

Certainly any time humans experienced a significant flood, some sort of oral history about it would emerge.

However, refugees travel taking stories of their experiences with them, and stories are retold and retold in various guises. So some proportion of flood stories would be repetitions of stories about floods that happened elsewhere.

It would be very difficult to pin down what that proportion is.

In addition some flood stories could be just stories and not have any historical basis at all.

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The high, the low, all of creation God gives to humankind to use. If this privilege is misused, God's Justice permits creation to punish humanity~~ Hildegard of Bingen cited in, Earth Prayers from around the World

So what do we make of the multiple coincidences? Details vary, but Wiki lists more than 20 flood stories (that we know of) from every continent.

I don't think there is any great mystery. There are multiple possibilities of actual floods, all of which could give rise to flood stories.

In addition there are multiple possibilities of flood stories being told and re-told in various ways.

If there were as few as five actual floods per continent (on average), there could easily be hundreds of flood stories.

It would be an interesting exercise to try and draw up a family tree of flood stories to see how many different types of flood stories there are and which ones were derived from earlier versions. One might also uncover hybrid versions in which a flood story from one family borrows elements of a flood story from a different family.

(Have you looked into memes?)

I don't expect there is much likelihood of connecting any particular family of flood stories with any historical flood.

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The high, the low, all of creation God gives to humankind to use. If this privilege is misused, God's Justice permits creation to punish humanity~~ Hildegard of Bingen cited in, Earth Prayers from around the World

Who says they are coincidences? Most human settlements are located on water of some type. Riverbanks swell and tidal waves break, so it's hardly surprising that there should be so many flood accounts.
(There are also many accounts of earthquakes around the world throughout history. This doesn't mean that at one point, there was a global earthquake.)

Also, could you please provide the wiki article you referred to?

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We can allow satellites, planets, suns, universe, nay whole systems of universes, to be governed by laws, but the smallest insect, we wish to be created at once by special act.

-- Charles Darwin