Of course all brains are physical. I used the modifier "physical" to emphasize the material nature of the source of consciousness.That one contains infinite volumes of discussion primarily because of the "consciousness" claim. Aside "consciousness" it certainly applies to humans based on all our observations. "Physical" brain? Is there some other kind?3. Not only is there no evidence that any consciousness can function without a living, physical brain, it is impossible to do so.
And you are right, there has been "volumes of discussion" about the nature of consciousness. Many insist that consciousness does exist without a physical support or that it is at least possible for consciousness to exist without a body. Note that the consciousness in question is human consciousness. Few people sit around wondering if that turkey they ate for Thanksgiving is living on without its body. They would think that considering turkey spirits is silly. How, then, is a human spirit any less silly? We humans privilege ourselves considering our own supposed afterlives while denying it to other species. In other words, our bias blinds us to the absurd nature of our beliefs.