Science Fiction

Well, it could be that the tech tree for intersteller travel is a road not taken by humans

hypothetically, I could see a rare case where a very advanced but very slow growing civilization, that has the technical capacity for interstellar travel (and indeed has far exceeded that level of technology) but for some reason simply never or rarely ever actually bothered with it, has their homeworld visited by a species that has mastered interstellar travel but only recently so. Or alternatively, a species for which interstellar travel is unusually easy, like some kind of hypothetical spaceborne organism that becomes intelligent but possesses no or only primitive technology, but can slowly move between stars without need for a ship, meeting an advanced but not yet interstellar planetary species. Some sci-fi has "space whales" or space amoebas or some other similar type of life, these would be what happens if such creatures got to whatever the rough equivalent of the stone age would be for such a thing.

honestly, that seems unlikely to me. uninhabited planets are abundant for resources, so we wouldnt really care about going for the very rare planet with intelligent life that poses ethical issues or some risk of fighting back, unless we were literally trying to use every scrap of matter in the galaxy which is bit more efficient and methodical than humans tend to be. Probably unlikely that theyd be biochemically similar enough to be safe to eat for that matter, beyond that most people would probably find that gross.

What I could see though is humans or some faction of humans thinking something along the lines of "they might be less advanced now, but someday they might surpass us or be a threat, so we should destroy/conquer/assimilate them while we have the advantage"

Thanks! Will check it out.