I would say that it can be used for someone who has passed on, but in the past tense. how could you say that about him he was a human being after all. they came upon a body, what is it? human. being implies incarnate or a soul shrouded in flesh. I heard a noise in the night, and demanded what form of being are you? being, does imply a soul or life form, I would only use it in a past tense for someone who is dead.

A human being means of the species homosapien