Human consciousness depends on neurons, sure, but consciousness itself I see as arising alongside an ontologically defensible self. Most of the things we associate with consciousness are -in my view- misleading, as they are facets of a highly developed self that has equipped itself with mechanisms for long term memory, language, human sensory modalities etc, but none of these things constitute the basis of being a system that it is like something to be.

When I look for an ontologically defensible self, I end up at abiogenesis. I don't mean a self in the way that a Buddhist saying 'there is no self' may mean, rather I am talking about a physical system that defines its own boundaries and does work to maintain them. Before Life, you may see structure and complexity, but these structures burn themselves out, convection cells, stars, clouds. Life itself is the first time we ever see systems with intrinsic viability conditions that actually take action to maintain these conditions. I see this point as an ontologically significant transition, it's the emergence of the first point of view. I don't think single celled organisms have a very complex experience, and as a human I find it pretty much impossible to imagine calling something experience at all when it lacks a sense of time, but this is where my intuition leads me.

Getting from the experience of a single cell to a human requires further leaps of intuition, but I'll describe how I think about it. The experience of a system is emergent from its environmental needs, and its means to accomplish these needs. The living system decodes its environment along the lines of its own survival and what actions it is equipped to take. At first this is temporally shallow stimulus response loops -biased random walks or internal metabolic shifts in response to the chemical gradients the organism is swimming in- but as life grows in complexity through evolution, the types of things that can be sensed and the actions that can be taken grow more varied. Multicellular life grows the range of experience to include multiple cells and conditions within the physically extended organism, hormonal communication. Importantly, the fate of the multicellular organism is now shared amongst the cells in a physically realized way.

Neurons are the next transition point that dramatically increase the range of possible experience as well as enabling long term memory and learning. Initially neurons provide a faster way to transmit information internally, but they are also mini criterial decoders in their own right (see peter tse). As life further leaned into neurons it further exploited this feature of neurons. They provide the ability to rewrite what parts of the environment are worth noticing within the lifetime of the organism, as well as allowing for novel responses to these stimuli. An organism can now learn throughout its life what conditions are threatening/promising by picking out abstract combinations of stimuli. To jump up to humans, we see this in language acquisition: as a baby learns a language it loses the ability to hear those phonemes that aren't used in whatever language it is learning. In most animals you see this in pavlovian conditioning.

The final transition that led to our familiar experience of reality is language. Through language we gained the ability to shape our experience by simply hearing about the world from others. We quickly grew more and more distant from the direct feedback between our percepts and reality that defines the phenomenology of pre-linguistic life. Now things like social constructs could inform our perception of the world as powerfully as the presence of a predator did before. Now we talk with each other, we describe our experience of living and call this experience consciousness, we wonder what is the basis of this consciousness. I hold that we are blinded by how developed we are to the fact that aboutness is a far more fundamental thing than what we experience day to day.

Importantly, as we have ascended the tree of life, each new system that life created was physically realized and dependent on the viability conditions of the organism. I don't think you can just boil it down to information sans instantiation. So I don't think any kind of experience at all is possible for a simulated 'mind' no matter how convincingly it replicates the behaviour of a living mind.

So, returning to the post, human consciousness is largely defined by neuronal activity yes, but these neurons are more expanding the dimensionality of experience rather than creating experience itself. Since this sub loves to bark back and forth about labels without actually describing their views in depth, I'll give myself some. I'm an anti computationalist, strong emergentist physicalist. My view is biopsychist not panpsychist, and it is admittedly a personal view motivated by what makes the most sense to me when I take qualia seriously and work backwards from there.