I went from ardently two-boxing to ardently one-boxing when I read that you shouldn't envy someone's choices. More general than that, actually; I had a habit of thinking "alas, if only I could choose otherwise!" about aspects of my identity and personality, and reading that post changed my mind on those aspects pretty rapidly.

Brain damage empirically causes damage to consciousness, so that pretty clearly indicates that the brain is where we get our consciousness from.

It causes damage to our ability to communicate our consciousness. For all we know, people with brain damage (and who are sleeping, unconscious, dead etc.) may be conscious, but just unable to communicate it with us (or remember it when they wake up

A concrete example might help. Consciousness could exist on some small quantum or string level, or other small level we haven't even discovered yet. It's possible that this level is undisturbed when we die, and that we continue to be conscious.