3 - It could be that liquefaction played a major role
in this as well. Liquefaction would occur as the moon would have been going around the planet, causing large tidal effects with no land masses to interrupt the movement of water.
The pressures in front of and behind the tides lifted and sorted the fossils each time there was a tide. Fossils are basically sorted by density in these
events, so it is possible that liquefaction moved whatever human remains there might have been to more surface areas where they would not have fossilized.
4 - Also, humans, unlike animals,
would know the properties of water. For example, they would know that water always finds its lowest point. Animals would not know this. Humans would know to get higher up
into the mountains to escape the rising water. Any animals that perhaps went up with them possibly became food for the people.