Was it inevitable that there would only be one remaining Genus Homo

Right, outcompeting doesn’t necessarily mean direct warfare (though in the case of sapiens vs. neanderthal, I suspect it did). As long as there’s something that’s providing a challenge to both species, one or the other will do a better job of standing up to that challenge. And every time that happens, the relative proportions of the two species will change. Eventually, one will die off, and the other will completely fill the niche.

There’s also the issue that we could interbreed. That likely contributed to the Neanderthals outright vanishing. The more numerous humans became the more any surviving Neanderthal lineages would to be simply bred out of existence even if we assume no violence was involved.

A Homo species we couldn’t viably breed with might be able to continue to hang on with much lower numbers just because they don’t risk being a single drop dispersing into the gene pool, as it were. Like chimps; they have no chance against us, but we can’t interbreed them into nonexistence either so for as long as we don’t actually set out to annihilate them, they survive.

We don’t reliabily act on empathy and emotional concern for others of our own species. Another species, similar to us but somewhat different – different enough to be "wrong " – would be the ultimate “other”. And you know what we do to “others”, don’t you?

Yep. Like how when we started building cities we had to put walls around them to try to prevent our neighbors from killing us to take our food. That’s how we dealt with limited resources.

Yeah. If they looked human we fucked them as soon and as often as we could. Or perhaps vice versa.

Usually both literally and metaphorically. Sometimes, when we’re feeling especially feisty, both at the same time.

I sometimes wonder if the Uncanny Valley is a relic of a time when there were other beings that were almost but not quite like us.

Which is why they are also called Homo sapiens neanderthalensis, in which case, they are still around- sorta. Many modern humans carry Neanderthal DNA.

But we out competed the others.

When you look at our recorded history, considering the wars and constant conflicts with the “out group”, regardless of how the distinction is made (color of skin, anatomical comparisons, social habits), it is unlikely that two groups would coexist for long. It seems to be an inbuilt animal characteristic to find or manufacture differences to further nefarious ends.

Eh, on the contrary; the world is full of coexisting groups. And even when fighting happens, outright genocide is the exception not the norm, the world is full of groups that lost wars but still exist.

If we really were that bad at getting along I expect we’d have never developed beyond small, mutually genocidal Stone Age tribes. That violently split with heavy casualties any time internal differences show up.

I see your point but I think you misunderstood the intent of the somewhat telegraphic title.
I read it as "“Was it inevitable that there would only be one remaining (member of) Genus Homo?”. The “member of” is implied. As is the “?” at the end.

But “we” are who we are because we’re also “them”.

When you look at our recorded history, there are always going to be multiple groups, because we’ll make them up if necessary. And they’ll always be interbreeding.

They died off because they were lacking in one or more vital survival components. It appears that our inability to control ourselves as a species and not be self-destructive is going to be the reason we die off, but the final chapter of our book has yet to be written.

Not at all. I was just objecting to the way it was worded.

Never mind…

And sometimes we even asked their permission before doing it. But always.

Not surprisingly, this is a long and, ironically, sometimes vicious battle between academics.

Personally, I think the issue is a classic thesis, antithesis, synthesis progression. Sapiens creates cooperating groups to fight battles, but also to farm land, build cities and infrastructure, and pass down information to children. Both individualism and group thinking have yielded major inventions, yet warfare brings about the fastest innovation. In-group battles persist but are eventually tamped down by social consensus. “Out groups” have always existed but so have societies which tolerate them to a greater or lesser degree - especially in cosmopolitan cities, a uniquely Sapiens creation that is vital to modern society.

Back and forth on and on, to different degrees in different cultures at different times. Most animals have an innate social structure that sticks for life. Neanderthal shows signs of group cooperation, probably because other primates had already evolved that, and its likely that our earlier ancestors did so as well. We’ll never know if they could take the leap to larger societies with far more variation, but I’d say that’s an absolute must for a Sapiens competitor.

If Neanderthals, or any other Sapiens competitor, had come out on top, it’s interesting to speculate if they would have eventually made it to the moon.

Pretty sure that even Neanderthal rocket scientists would wear white shirts with pocket protectors.

The Neanderthals would have never developed religion and a concept of life after death, and would have been exceedingly cautious with their lives. Therefore they would never have attempted a moon mission.

My source:

Urgh.