You seem to be equating 'consciousness' with simply 'being a living creature that has a nervous centre'.
If that were true, it would mean consciousness has no meaning, since it is indistinguishable from simply having a nervous centre. They would be synonyms.
They're not. Consciousness means a qualitative property more than simply having a brain.
When an organism "responds" to external stimulus it is "experiencing" the stimulus , no?
According to Hameroff and Penrose, this experiencing already happens in single celled organisms.
Any organism which has micro-tubules (scilia) experiences a small "bing", due to the probability that micro-tubules are very small dedicated quantum computers, which process a quantum wave-collapse as a true experiential event, to which the organism responds.
What would be the problem with that? Could it be a little hubris to think that we are the only organism which can mentally process and respond to specific sensory information in a specific way?
When I was raising chickens, I had a rooster who would stand watch and warn the flock when something of concern presented itself. The interesting part was that when the perceived threat was ground bound he would use low tones in his crowing, but when the threat was in the trees or sky, he would crow with a high pitch. Each type of warning resulted in a different behavior in the flock. When the threat was on the ground (in the brush) the chickens would rush to the covered pen and gather, when the threat was from high up, the chickens would take cover in the brush. When I first noticed that different response to a verbal warning in chickens, I was really intrigued. Have a listen to this!
I am not speaking of abstract thought, which is a very sophisticated model of sentience and consciousness. But why should consciousness such as feeling pain, warmth, cold, affection, belong only to a few hominids?
How about apes, dogs (land animals).
Or whales, octopus, cuttlefish (ocean animals).
Or birds, which dwell in both mediums. Penquins, sea-otter?
The question is where is the treshold, a "blind" physical response to stimulation or "knowing" your response to stimulus?
I just believe that living organisms posses communication methods and awareness far beyond what we normally assume from our own "limited" knowledge of animal languages.
Koko, the recently passed lowland Gorilla, had a beautiful poetic mind and great depth of emotionsl responses with her interactions with humans.
Think of this - she chose a Manx (no tail) kitten from a litter and named it "All-ball".
When the cat was later runover by a car, Koko wept and mourned her loss by signing; "All-ball not come back". I find this astounding abstract thought. It brought tears to my eyes.