I suspect some of the reactions to this article have more to do with the mismatch between the title and the content than anything else. The title claims that we "know" what consciousness is, but the text doesn't support that claim. Rather, it argues that consciousness is fundamental to existence.

There may be a valid point there. At least, the idea that we don't really know what anything is has validity. Richard Feynman once wrote that about the concept of energy, saying (in essence) we know how energy behaves, but we don't know what it is. (Once when I posted that, someone argued that, no, Feynman knew exactly what energy is; so I guess he thought the physicist was pulling his readers' legs or something?)

The point people often miss is that models of the physical world are just that: models. They are not reality, only maps of reality as we understand it at a given point. The maps do change over time as our knowledge grows, and they are often based on assumptions which, although generally reasonable given what we know, could prove wrong. Reality is always right. The models are not, and even when they are nearly right, the map is never the territory.

This doesn't mean that a tree that falls in a forest makes no sound if nobody is there to hear it. (I don't know why people got that from your article. Clearly, that's not what you're saying.) At the same time, it may be overstating it to say that consciousness is fundamental to existence. At best, what you've argued is that consciousness is fundamental to our understanding of existence, although that's probably tautological. (Of course consciousness is fundamental to our understanding of existence. Without it, we couldn't truly understand anything.) But it says nothing about what consciousness actually is. And therein is the dilemma. There has been a lot of hype over the past few decades about using machines to fathom the nature of consciousness. But even if a machine could be conscious (something I doubt, but I won't commit to that 100%, at least not in public!), there is no reason to think that making it so would tell us what consciousness is, any more than all our physics tells us what energy is.

So to make a long story short (too late!), I think your article is mostly on target, but the title? Not so much.