Are there any examples from human history where explorers have arrived on “new” land and have then been defeated by those already inhabiting it? It seems like those arriving tend to have more advanced technology and even when they’re starving and weak manage to conquer. For humans, at least, I suspect “victory” goes to the visitors far more often.
But if, by some miracle, the humans prevailed I think you’re unfortunately correct about us conveniently ignoring the lesson.
Europeans in North America. For a long time any colony that was founded only survived if the natives allowed it. Yes, the Europeans had guns vs. bows and arrows, but the guns at the time sucked. Bows and arrows were faster to fire, faster to reload, and had better accuracy.
It wasn't until some tribes that were not doing well in wars with other tribes made alliances with the Europeans that Europeans really started to get established.
Later the diseases that came with the Europeans tore through the whole continent, rapidly reducing the native population by over 90% and then Europeans could pretty much take over anything they wanted to.
The Road Not Taken by Harry Turtledove
(It's a great, short sci-fi story for anyone that may be interested. It should be pretty easy to find the PDF.)
Then, of course, they'd be weak from the journey, and we'd kill them and find a reason to ignore the obvious lesson.