I think it's fair to say we do know that we have a somewhat physical brain. Even if it's part of a dream then our definition of "physical" would be scoped to that dream and still be accurate
I was just talking about the physicality of the brain, so it'd be (physical brain)->consciousness vs. consciousness->("physical" brain). Either way in all ways that matter to us the brain is physical.
I think of it similarly to how atoms are mostly empty space - we can know that's true but the main thing that matters most of the time is that you don't fall through the floor, so we reason about the world as if solid objects are actually solid
