…Seems legit.
…Sea faring tribes and humanity (or at least a select few) knowing of the oceans & how to navigate them, long before we've been 'taught'. Add a shifting of Earth's axial tilt (and water table displacement), the grand storms and earthquakes.
As for the elongated skull thing, anon is aware 100% human, but still stuck on it's inspiration/origin. Each 'species' being successful genetic mutation. A little interbreeding (isolated biological life after ) and environmental factors favoring certain generational 'traits'.