How can they be sure that the “Neanderthal” was not just a larger-boned, different human? If they can tell a white person, black person, Hispanic from a SKELETON why can’t the Neanderthal just be a human that was say in a pocket of the world that didn’t get out much, like those aborigines they’ve found around the planet? My husband’s uncles had heads just lie that Neanderthal. ;)
I am not convinced they are something other than human.
There are morphological differences between someone living today and the fossil remains of people who used to live; among people with European ancestry, Neandertal morphology has persisted, and isn't found among other living groups. Genetic sequences from the Neandertal are likewise found in living people of European ancestry, and not elsewhere; this mitigates against either the genes or the morphology from having been in the much older, common ancestors.
The notion that Neandertal is somehow inferior seems to have originated with Virchow, who really circled the drain, until he went over the lip into the pipe by claiming the Neandertal remains were just those of 18th c Cossacks with rickets who'd died naked in a cave after fleeing from a battle where they'd been defeated (they stripped off their uniforms, which were their only clothing, then died of exposure).
The racial-supremacist Replacement Model requires that Africa is the only origin of all living people, and grows out of Chuck Darwin's pretty tales.