To your first counterpoint; I can see where you're coming from, but the validity of this point hinges on whether the cube was possessed of enough sentience and intelligence to actually adapt in the first place, which I still contend runs contra to what we've seen from the Borg previously.
But since this was specifically and intentionally a situation we haven't encountered before, we can't really definitively say it's inconsistent with what we've seen previously.
To your second; no, it has not been explicitly stated, as is the case with most Treknology, we must make logical inferences from the information that is available and what we can see on screen. Whether the original Borg concept was backwards or not isn't really at issue, they are an established fictional race with established features, and none of those established features support the concept of sentient cubes.
I think the concept that the Borg have sapient AI is a logical inference from what we've seen, and the concept that they don't is not a logical inference. The Borg have always tended more strongly to the cybernetic than the organic. We know the Queen must be a program rather than a living being, since she re-embodies elsewhere after a given body is destroyed. More broadly, we know that sapient artificial intelligence exists in the Trek universe, we know the Borg have existed long enough and spread far enough that they've surely encountered it before, and we know that the Borg assimilate any technology they find useful.
For that matter, we have multiple precedents in the Trek universe for even a non-sapient computer spontaneously evolving sentience in the right circumstances: Moriarty, the "Emergence" entity, Voyager
's EMH. So even if we stipulate to your premise that a Borg cube's cybernetic systems are, for whatever reason, no more intelligent to start with than a Starfleet computer mainframe, that still doesn't rule out the possibility that they could become self-aware in unusual or extreme circumstances.
Regardless, I still cannot see why this is a unique situation. There have been numerous instances shown where massively damaged cubes have been cut off from the Collective with most or all of their drone populations killed, particularly during the war with 8472, yet those cubes were never shown as anything other than inert technology. Wreckage.
Yes, that's exactly the difference. In those cases, the physical technology was massively damaged along with the organic drones, or instead of the organic drones (for instance, in "Collective," the technology was fried but the juvenile drones survived). The technology wasn't just wreckage because the drones died, it was wreckage because the technology itself was physically destroyed, taking the drones with it. This is the opposite case, a circumstance where only the organic components of the cube were neutralized and the technology left essentially unharmed.
I just keep coming back to the same thing; there has never been any prior indication that cubes are sentient, or that they need to be so.
Even if that were true (and I don't agree that it is), that was the whole point of the story: that what we were seeing was something new resulting from extraordinary circumstances. There was never any indication prior to "Elementary, Dear Data" that a holodeck character could become sentient, but it happened there, and happened again later on.
The Collective consciousness is the Borg, without that, nanites become dormant, drones revert to individuality or die, and without those to maintain it - technology becomes inert. For me personally, it's simply too much of a stretch to assert out of nowhere that, well, actually, cubes are sentient see?
But you're making the entirely unsupported assumption that the collective consciousness consists solely
of the organic minds within it. When have we ever
been given any reason to believe that? We've always been shown that the Borg are a complete symbiosis of the organic and the technological. It's completely misunderstanding them to treat the technology as mere support for the biology, when all along their actions have shown just the opposite, that their organic components (drones) are treated merely as subordinate adjuncts to the governing machinery. Or, at most, that the Borg consider both biological and technological components to be of equal and interchangeable importance.
And they're made up of nanites, see? Oh yes, and they can also puppet drones, and make "pseudo-queens", and suck people into walls, and and and etc etc.
Agree to disagree I suppose.
All of those are extrapolations from things we canonically know to be true. We know their technology includes nanites and is grown by nanites, therefore it's not a fundamentally incompatible premise to posit that their technology could be fully nanotechnological. Even if most Borg technology isn't, this was an outlying cube that Resistance
already portrayed as having some differences from most Borg populations we've seen (such as being sexless by default), so who's to say it couldn't have had some unusual variant of Borg technology as well?
As for "puppeting drones," that's what they always
do -- the drones are merely peripheral devices controlled by the collective consciousness. I don't know why you'd think that's anything new. If you mean the technology manipulating a dead drone body, zombie-style, we saw something very like that happen in VGR: "Unity." The Doctor inadvertently activated a backup power cell in the dead drone he was autopsying, causing it to rise up and flail around. That proves, canonically, that it is possible for a drone's cybernetic components to cause it to move without there being any living tissue within it.
As for making "pseudo-queens," how is that any more implausible than their ability to assimilate people in the first place? After all, the Queen is simply a specialized drone that contains the Royal Protocol, the software that's essentially the Borg Queen's consciousness. Homecoming/The Farther Shore
already established that the Protocol can be downloaded into an assimilated drone. There may be some variations in the way it occurs in Before Dishonor
, but there's nothing about the basic premise that's implausible or inconsistent in light of what's been established about the Borg in the past.
As for the walls being dynamic and mutable, able to change shape or suck people in, I've already pointed out that we have canonical precedent for this going back to "Q Who," when we saw a damaged portion of a Borg cube healing under its own power, morphing back toward an intact condition. So that ability has been implicit in what we've known about the Borg quite literally from the beginning. This was merely an extrapolation from existing canonical precedents.