But then again, to them their ways seemed perfectly logical and sensible, and until the Europeans arrived they had no reason to think beyond those constraints or even consider them to be constraints.
Um... those "constraints" are somewhat mythical. I think they're a remnant of the "manifest destiny" nonsense. More recent research gives us a different perspective.
Let us consider, first off, that "sale of Manhattan for beads" bit. That entire story comes from one document - a letter written by a Dutch trader. We should note that the letter does not mention who they bought the land *from* - like, we don't know if the Dutch identified that the person they were buying from had any authority to make deals! In all probability, while the Dutch thought they'd bought the land, the Natives felt they'd made payment to be recognized as having a right to stick around. Note that the deal itself didn't actually impact things from that point on - it isn't like the Dutch used their "ownership" to evict the natives.
Note that the concept of "I own this land, and therefore get to exploit it" only helps you if your ownership rights are recognized and respected by others - you need others to recognize and honor your ownership. Given how frequently Europeans broke agreements, contracts, and treaties when they became inconvenient, I don't see how having the European mindset would have helped. The natives would have gotten pushed aside even if the Dutch hadn't "bought" the land.
And, the assertion that Native Americans "did not exploit the land, expand scientific and technological advances," is likewise inaccurate. I'm sorry, but it shows an ignorance of how Europe got its technological advances - by having the luck to be able to build on the advances of Mesopotamia, the Persians, Greece, and China. It shows an ignorance of how great an impact horses had on European and Asian advancement. It shows a lack of understanding of the massive agricultural workings of the Central American empires (Not exploiting the land? Ha!), and that many of our current agricultural products are based on strains originally bred by the Native Americans - corn, potato, tomato, bell pepper, chili pepper, vanilla, tobacco, beans, pumpkin, cassava root, avocado, peanut, pecan , cashew, pineapple, blueberry. It misses how North American settlers remarked on finding entire forests of fruit and nut trees set up as orchards (which, of course, they cut down and cleared). It misses how quickly Native Americans adopted and mastered horses. It also misses how much math you have to know to create something as accurate as the Mayan calendar. And those are only the big colorful examples that pop to mind.
Basically, the whole "Native Americans didn't have the mindset for advancement" is a myth (and a kind of racist one, I'm afraid to say), based on ignorance of what was going on in the Americas, and of how lucky (dare I say privileged?) the Europeans were. Europeans were not special in their mindset, but were special in their location and situation.
Isn't it just as likely that we are operating under similarly universally-held, never-questioned assumptions, and will be similarly utterly unprepared to deal with the wider realities we'd be exposed to by a truly alien spacefaring species?
Given how persistent things like Janx's assessment of indigenous people seems to be, even despite evidence and research to the contrary, I'd say that's an ironic "yes!"