with regards to your theory about already being dead....you never know because we don't know what life after death is like......

check this

what if what we live is actually a dream and when we are asleep is when we wake up, and what exists in reality is just what our mid has the power to generate, which could explain why sometimes we have vivid dreams and sometimes we don't. it could be because sometimes we don't wish to generate something from our minds....and assuming we're dead and already departed then that means there would be nothing except the mind and its products. and maybe the mind's capabilities multiply to such a great extent that it can fall into complex dreams, which we percieve as "reality".

funnily enough that would tie in with my 1st theory seeing as if life's a dream then obviously it would revolve around oneself and could just co-exist with my second theory as we would still be dead................