It IS all physical. It's also an unimaginably complex fucking shitload of tiny physical objects working incredibly quickly. If your brain was big enough to see the parts working like little gears of a clock, it would probably be planet sized, or something like that. Huge.
I would EVEN say it doesn't raise any interesting philosophical questions. Are computers silicon, or magic? Is a book paper, or magic? Is the economy magic, or a bunch of people buying shit everywhere?
Knowing that the brain is physical doesn't make me question myself or doubt control over my life or any silly shit like that. Yes all of my actions are technically "predetermined" by the Big Bang, but not in an interesting way, at all.
Semi-related, if you made a giant brainlike calculator out of water pipes and valves and shit, and asked it a question, then turned all its pipes and valves for a while... it would probably just say "please kill me."