Optimistic Nihilism.
Consciousness is an accident, the universe is an emergent property of physical laws, and there is no purpose to any of it; no gods, no guiding intention, no natural morality, no afterlife. Just entropy.
This is a good, positive thing to understand.
If there is no intrinsic morality, then we are free to define morality for ourselves. This is a burden, but it something that we can recognise and think critically about, rather than just taking whatever tradition we were raised in, and picking and choosing as is convenient.
If there is no afterlife, then every act of alturism, every kind thing we do we can do because we want to. Not because we are afraid of damnation, but because we decided that it was the right thing to do.
If we leave nothing behind but dust, then we must be aware of the impact we have now, because our time is limited and brief.
If we are a random collection of atoms, a brief coherent pattern among the chaos, then we can recognise that every single other person is the fundamentally the same.
Hard determinism. Everything is a number and has already happened. Also, one electron universe.
Optimistic nihilism has always been a favorite. While there may be a purpose to existence, there is no concrete evidence of it. But if indeed life has no meaning, that’s not a big deal, because humans are creative and can create our own.
We aren’t special. Conciousness is a side effect of having so many neurons shaped by millions of years of social and environmental darwinism. We are actually barely concious to avoid confronting the fact that we are just walking meat.
If human head transplants were done, we would have proof that the soul is just a sophisticated algorithm held within our meat, but even then, our barely concious state will refuse to compute the actual implications.
Further our “singular conscious” is an illusion. People with various types of physical brain damage have had their awareness “split” and had something akin to two different consciouses in their brain. Even for “normal” people there are independent processes running in our brain. Our consciousness is in charge sort of the way the teacher is in charge of the nursey school. It might decide when recess is but it can’t stop that one kid from just singing for no reason.
Also to your point I think that if we could transplant a head we’d find that our sentience involves more than the brain. I think we underestimate how connected all of our systems are.