I think it can all be explained with materialism as consciousness can be mapped on an MRI. Cats are conscious, insects are conscious. It's a trait of life.
However, with that being said, there's the feeling we have of subjective experience that you and I personally endure. The feeling of being a pilot in this body. One second your experience doesn't exist, and then bam, you're plugged into +/-5 senses.
You could call it a soul, or a pilot, or subjective experience. But whatever it is, many debate on whether humans are the only ones with this piloting experience.
Is a cat just a complex network of passive inheritance and coroutines, an automated existence?
Is there a threshold where this piloting experience starts exist or does everything experience it?
Is something as simple as a single cell bacteria capable of receiving a pilot?
What about simpler things?
If we find out later, that robots have souls inhabiting them without us knowing, does it change the way we use them or do we recognize that the experience could not possibly become bored as this is a biological trait?
Could it get to the point where it would be cruel to let any biological life exist simply because they can suffer? This goes very very deep, and I can't see the end of this tunnel.