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That is very likely to be true. In our own analyses we found that within ~2.5 weeks of showing up it has pretty much replaced Delta. So there are a few things related to that. First, yes ACE2 receptors are docking sites of the virus and in Omicron one piece of the puzzle seems to be that the spike protein-ACE2 receptor interaction is much tighter than with earlier variants. However, the upper respiratory tract has also high levels of ACE2 receptors (as well as other organs) and the upper respiratory tract is known to be an entry point also for earlier variants (the often reported loss of smell is one of consequences). The question then becomes why it does not spread or colonize the lungs that efficiently. There are are several lines of investigation underway to look at that. In vitro studies suggested (Zhang et al., cannot recall the journal of the top of my head) found that two additional serine proteases promote the entry of SARS-CoV-2 (TMPRSS2 and 4). Conversely, Omicron seems not to use that pathway to enter, instead using a TMPRSS2-independent endosomal fusion pathway (i.e. a different way to enter after docking). These proteases are abundant in the lung, but much less so in the upper respiratory tract which would at least explain much higher efficiency in colonizing the upper respiratory tract. That being said, this data alone does not entirely explain why they seem to colonize lungs somewhat less efficiently yet.

It's great that it wasn't more severe. Looking at the current spread we are somewhat lucky that it only arrived after vaccines were available and more expertise in treating patients have been developed. If the first or second wave happened at that speed, the outcome would have disastrous, even if severity was lower on the individual level.

I think it is still very much open. GR is an accurate and very valid description of gravity (within its domain of applicability), but it isn’t an explanation, because it has nothing to say about the underlying mechanism. We simply don’t know yet how and why macroscopic spacetime with its observed degrees of freedom comes about; we can only describe its dynamics. This is why research into quantum gravity is so important.

As to emergence there is, I think, a dilemma between principle and practice that I think overrides almost any other consideration. Directionality of emergence is very clear in principle, but there are insurmountable difficulties in practice to ellucidate causation. Atoms make a dog. Dogs don't make an atom. It's what Weinberg called 'arrows of explanation.' That's very clear in principle. Even though it's impossible in practice to tell anything about dogs from the laws of atomic motion. It's very clear to me that dogs emerge from atoms; atoms do not emerge from dogs. I happen to know that some very philosophically-minded people think otherwise, which are the ones that @TheVat characterises as 'strong emergentists.' I think they can do that, only because the 'arrows of explanation' are invisible to all intents and purposes. It's a hopeless problem, so there is room for people to exploit this practical disconnect, interpret it as fundamental, and what's more, invert the 'arrows of explanation.' In this example, I think people who hold this view are disregarding an approach that's much more plausible: feedback mechanisms. Those are compatible with molecular determinism, IMO. Even though they're extremely complex. An algorithm to run on a machine that proved beyond any doubt that there must be such a thing as a dog based on the quantum laws of motion. That would be a sight to behold. But I wouldn't wanna be the person analising the data. This would-be machine would have to prove the logical necessity (from the atomic laws, to be kept in mind) of giraffes, and T-rex, and gut bacteria, and... covering all the organisms that ever were, that ever will be, and that would have been.

No. I used octopuses, primarily, because you recognised their intelligence and I thought that similarity might overcome your assumption of authority; humanity is just part of, not more than (read my signature)...

Covid is transferred on droplets. Those droplets were once part of another human. The atoms of the virus were also once part of another human. And covid isn't the only virus. If you smell my fart, your nose has trapped atoms from my body. Your lungs would also retain some of the fart atoms or fartoms, as they are know by biologists.