Alan Guth concocted inflation theory in 1980 to avoid evidence for a 10,000-year-old universe. For his wild, evidence-free speculation, he may win a Nobel Prize.
A claim of vast reservoirs of water deep in the earth is based on indirect evidence, and likely has little or nothing to do with surface water or floods.
They were our physical and intellectual equals. What's the difference? The label "Neanderthal" becomes a kind of historical racism against a group of true human beings.