There is a somewhat analogous issue in physics, that of energy. Both sentience and energy can only really be grasped in terms of that they do, rather then what they are.
For example, what drives a wave is energy, yet we think of the wave in terms of the forms it expresses, the fluctuations and undulations that give us frequency and amplitude.
Similarly what drives our actions, reactions, thoughts, feelings, perceptions, etc is sentience, yet we tend to see the form of perception and thought as more real than what drives it.
Which goes to one of my pet obsessions, that we view time backwards. Sort of like we view the sun and stars as rising in the east and setting in the west, rather than the ground underfoot spinning west to east.
As these mobile organisms we have a sequential process of perception, in order to navigate, then as members of humanity we have a narrative based culture, so we think of time as the point of the present, moving past to future, rather than change turning future to past. As in tomorrow becomes yesterday, because the earth turns.
There is no literal dimension of time, because the past is consumed by the present, to inform and drive it. Causality and conservation of energy. Cause becomes effect.
So energy is "conserved," because it is what manifests this state we refer to as the present. The changing configurations are the effect of time. Similar to temperature, pressure, color, sound, etc. Frequencies and amplitudes.
As these organisms, we have the digestive, respiratory and circulatory systems processing the energy driving us on, while the central nervous system sorts and organizes the forms precipitating out.
So consciousness/sentience, like energy, goes past to future, as the forms, whether physical frequencies and amplitudes, or mental perceptions, thoughts, emotions, go future to past.
Our perceptions and thoughts are like the cresting waves. They are most clear as the waves are cresting and most fully defined, while our emotions and intuitions are like the temperatures and pressures of the waves building and receding. We sense them, but they are not clear. Thus the sense of the present as a point, quickly receding.
So the mind is more the shutter, aperture, lens and filter for this sentience, than the energy/light that is its source.
Though what drives us is the desire for the sources of this energy, like fuel for the flame within.
As consciousness functions as a sequence of perceptions, the sequence seems foundational to our concept of reality, but it is emergent. Consider that causality is energy exchange, transformation. The batter hitting the ball causes it to fly away. Though our perception of it is a sequence of events, not the actual energy.
Consider that yesterday doesn't cause today. The sun shining on a spinning planet creates this cycle of days and nights. So our perception is more the progression of events, than the processes creating them.
Just some thoughts to consider, when evaluating sentience.
We are fauna with a highly specialized ability to process information. Unfortunately we allow the process to be corrupted and those most pathologically obsessed with social power to control our societies. We have a long way to go, before we really rise above our basic biological origins.
