The simplest definition for consciousness is a subjective experience. This definition doesn’t include ill defined concepts like feeling, or restrict consciousness to any subset such as living things or people.
We’ve already made progress on figuring out intelligence. That was the easy problem because we had ways to tell when it was working, and we could quantify it.
If intelligence is the easy problem, then the next hard problem is determining when something is conscious. We aren’t even close to a consensus on this question, and much further from answering the really hard question of why does anything have a conscious.
The only way to prove a subjective experience is by relying on the nature of the subject. We need to identify the parts of the brain responsible for the specific experiences. Then we can start to understand when something is having a conscious thought.
The parts of the brain we found as responsible for areas of our awareness and skills, aren’t necessarily the centers for our consciousness about those action. They could be only pathways that we notice when they are disrupted of used.
The visual illusions that trick our eyes, feeling of pain in different places than the injury, or phantom limbs felt by amputees show that consciousness lies somewhere deep in our mind; in a place we have yet to find.
In fact, our awareness of the current moment is delayed by about a quarter second. Yet, you can react and even make decisions before becoming fully aware. This is why an Olympic race is started by a sound instead of a visual cue.