A very fundamental question that no one has answered yet and few people even ask is this: does the brain produce consciousness/mind/spirit or is it the other way around?
This is not an interesting question. You are essentially asking if the universe is based on physics or mysticism. Idealism is absurd, Dualism leads to unanswerable questions and Materialism seems to be working out pretty well for us.
It's not quite as black and white as you make out. You don't have to believe in "mysticism" or "idealism" to know that consciousness exists. Cogito ergo sum still seems true to me.
Cartesian dualism might produce unhelpful consequences , but you can't handwave it away simply by saying there's no such thing as mind or consciousness.
If consciousness can't be explained by pure materialism, then pure materialism is an incomplete theory.
There doesn't have to be a magical explanation for something that we don't (yet) understand, but that doesn't mean we can simply write it off as imaginary.
This isn't like talking about the existence of gods or an immortal soul. I have no direct evidence for them, whereas I do for my self.