There may be other forms of consciousness we cannot understand. Nonhuman animals’ precise relationship to human consciousness doesn’t make them less important.

A different take

We still do not know what makes the difference between being alive and having consciousness.

Octopi and other cephalopods have nervous systems throughout all their limbs. Their bodies are not a separate thing controlled by a brain or central nervous system.

So, measuring consciousness using a central nervous system like ours may lead us to believe they do not have pain capacity or even sentience. Yet behavioural studies show they express both, just differently to humans