I don't think the collision happened when there was water, but rather when Earth was still cooking with gas. (Not too sure about that claim, it may be based on the computer generated graphics they always show in the many docs of the formation of the Earth I've seen.
There's a theory about the Moon forming from the debris of a collision ~4.5 bya, but the scene in Genesis already has a water covered world waiting for God to create land and life. That makes the late heavy bombardment ~ 4 bya the prime suspect given its proximity in time to the oldest continental rocks and life. We have evidence of water going back ~4.4 bya so the proto-Earth had already cooled enough to have an ocean by 4 bya.
And that didn't spatter the moon, it formed the moon. So maybe we're not talking about the same thing. In fact I'd like to see some evidence of: "those dark spots on the Moon are there because we got blasted by something and it happened "shortly" before we have evidence of plate tectonics and life." I haven't heard of that before.
The Moon was a witness to the collision(s) that ripped the proto-Earth ~4 bya, the side facing that cataclysm still faces us today. I believe this collision is what triggered the late heavy bombardment, but only time will tell. The dark spots or "maria" (seas) were blasted out depressions that filled in with lava over the next ~1/2 b years. Compare it to "the dark side of the moon".
One thing is for certain, you cannot claim they had knowledge. You don't know that. And I addressed the many myths around the world already. Norse mythology had 9 worlds. And they did include fire. So they were closer to the truth in that regard.
The world tree had 9 branches, the world mountain had 9 peaks, 9 levels in Dante's Inferno, the Toltec had 9 Lords of the Night (Chichen Itza), Siberian shaman prayed to 9 small trees, The Incan Genesis depicted the creator as an ellipse separating 9 "stars" into groups of 4 and 5... The Nazcan monkey stares down between hands with 9 digits (4 & 5) on 2 hands. The horned deity at Newspaper Rock, Utah, being shot at with arrows by the creator accompanies 9 celestial "sheep" and is both the 4th and 6th "planet" just as the Enuma Elish places Tiamat in the solar system - and there are 9 planetary gods described in the Enuma Elish joining the Sun before Marduk is called upon to battle Tiamat resulting in the "creation" of Heaven and Earth. The list goes on and on...
oh yeah, the Enuma Elish describes the fiery death of Tiamat and her rebirth as the Earth...
They didn't have knowledge beyond their observations.
Peoples in both the old and new worlds depicted the solar system with more planets than can be seen with the naked eye, and that was what Democritus reported upon returning from Egypt and Mesopotomia.
edit: How about the Chinese. They claim humans were created from yellow clay and talk about a creation of an egglike world. No, Genesis and pagan myths from all over the world do not say the same thing. The ones you decide to cherry-pick do. Do a random selection and then see which ones say the same thing.
So you edited your post to accuse me of doing what you did in your edit?

You cited 1 myth when we have a world of myths - and HB asked me to offer any religious text in support of my position and he'd shoot it down. I didn't say every myth you can find says the same thing, but another Chinese myth says the creator was in the sky hammering out rock and throwing it down to a world covered by water thereby creating the lands. They do have the same myth...
Because they didn't use 4B as a number. They just said that in the beginning the Earth was covered in water. Then you come along and say, well, at some point the Earth was covered by water, so they were right.
They said it was covered by water immediately before the creation of land and life. That looks to be true... They were right but you said their mythology was BS.
You see the exact same thing when people try and apply prophecies to following events. The fact that it might eventually be correct does not make the prophecy a scientific statement.
a prophecy is about future events, not about Earth history
In the beginning of God's preparing the heavens and the earth -- 2 the earth hath existed waste and void, and darkness [is] on the face of the deep, and the Spirit of God fluttering on the face of the waters
(Young's Literal)
See how the Earth "hath existed" but darkness and water covered it? Earth is the name God gave the dry land that appeared when the waters were gathered into "Seas". That doesn't happen until the 3rd day:
9 And God saith, `Let the waters under the heavens be collected unto one place, and let the dry land be seen:' and it is so. 10 And God calleth to the dry land `Earth,' and to the collection of the waters He hath called `Seas;'
Nowhere in the Bible that I know, certainly not in Genesis, is it claimed that God created the waters - the waters in Gen 1:2 were already in existence, so was the "dry land" but it was submerged. As for Heaven:
6 And God saith, `Let an expanse be in the midst of the waters, and let it be separating between waters and waters.' 7 And God maketh the expanse, and it separateth between the waters which [are] under the expanse, and the waters which [are] above the expanse: and it is so. 8 And God calleth to the expanse `Heavens;' and there is an evening, and there is a morning -- day second.
So the heavens and earth dont appear until the 2nd and 3rd days... And what is Heaven? An expanse? The akkadian term is rakia, hammered out bracelet (compare with above Chinese creation myth). Firmament was an approximation but you can see how the terms have lost some of that imagery - but whatever Heaven is, it came after the waters and served to separate them.
Berzerker has a particularly odd conspiracy theory related to the creation of the Earth and his opinions are apparently as unshakeable as those of YECs.
I've been trying to shake it for ~3 decades after first learning about this theory, and I can honestly say the theory has done nothing but gain credibility with me as we learn more about the solar system. The Enuma Elish combined with cylinder seal VA 243 show people living in the land and time of Abraham had access to knowledge we're still discovering.
Berzerker desperately needs a class in comparative religion.
You should see my library