To me, invoking 'laws of nature' like
@TheMadFool has done equates to subatomic particles behaving in certain ways
just because. Panpsychism, as I understand it, says that everything has a
mind of sorts.
I tend to think that consciousness and self-awareness can only exist in our physical world when there is a brain to produce/hold it.
Quarks, atoms, molecules and such appear to be the 'simplest' forms of matter, and seem to have a life of their own, despite not having physical structures that would allow them to think. For them to be able to combine into living systems, there would have to be some sort of guidance involved (i.e. the 'laws of nature' would have to be programmed into them, so that that they consistently behave according to a set of rules). Kind of like how electricity has certain reliable properties, and can be used to bring a computer to 'life' by constructing the circuitry just so. I can't see how there could be consciousness or self-awareness at this level. (e.g.
Man, being a quark is really hard work!).
My guess is that essentially inanimate objects like rocks have no consciousness - they are just assemblages of particles that are affected by surrounding forces.
At the next level you have things like cells, that move with purpose, can reproduce, and can organize themselves to form part of a greater system. With no brain, there is likely no consciousness or sense of self.
Let's move on to plants. They can slowly respond to changes in stimuli (e.g. a flower will open during day, and close up at night, according to the amount of sunlight), but seem to be no more than a collection of different cell types, each with their own function. They have cellular systems that will act and react in order to survive and reproduce, but it's hard to imagine them
feeling pain, or having awareness of existence.
Now insects. Here, while there is no ability for things like language and self-reflection, I am guessing there is an ability to
feel pain, and to know that it sucks (even though they can't always express it in ways obvious to humans). I tend to imagine this level of brain kind of like the empty, wordless state humans can achieve through meditation - awareness of being alive, able to observe stimuli, and a sense of what's good and bad in terms of survival and avoidance of suffering.
This is getting to be a bit long, so I'll just write that between insects and humans, I would say there is a spectrum with increasing levels of consciousness and self-awareness.