Until now, we only had fragments of these cousins. Now we have face. Studying our evolutionary development and our sister-species is one of my favorite aspects of archeology. We’re constantly developing new information.
Side note: look up the initial presentation of Homo naledi. The leading archeologist did a phenomenal talk a couple of years ago (I think in December). It was really an exciting presentation. But I’m also pretty nerdy.
You seem to be focusing on intelligence which hasn’t been considered a particularly big factor past like homo-habilus since the 70s, Homo-sapiens were the most adaptive which basically allowed us to exist in any environment. Our biggest strength was our thermo regulation everything else was sub standard compared to the other human populations, but because of our weaknesses we basically had to pursue more advanced technology to compensate. A neanderthal could take a hit from a wooly rhino a Homo-sapien could not, so we made spear throwers and improved the spearheads.
Secondarily neanderthals killed each other about as often as different tribes would interact, this could actually explain their absurd level of population spread compared to actual population size. This population spread is also why they were going extinct before homo-sapiens moved into Eurasia, they were getting pretty damned inbred in a lot of areas.
Mankind is a prime example of survival of the fittest, we weren’t the strongest, biggest, or even smartest, but we were the most stubborn and willing to fuck everyone out of existence. Seriously a new consensus is that most of the other African homo went extinct because they started to interbreed to a massive degree, which Homo-sapiens emerged out of.