I sincerely don't know what you mean by "human being". When I ask myself what 'human' means, I only come up with an answer that relates to genetics ('this DNA is human', or, 'this DNA is salamander') and I suppose 'being' might relate to some notion of being a complete, living entity.

I'm further confused because giving even the fullest notion of 'human being' (e.g., sapient), we still sanction killing human beings in some contexts.Whether or not it is moral to kill someone doesn't seem to rest on whether they're human. (Maybe adding the word 'innocent', for example, seems too obvious in the case of a baby. But then I least I would be able to deduce that you believe it is immoral to kill any innocent human.)