Depends on the context.
   Dictionary definition:
   Human:
   a human being, especially a person as distinguished from an
   animal or (in science fiction) an alien.

   So that's a start.

   But:
   "What does considering myself "human"
   accomplish with regards to my sense of
   identity and purpose?"
   That's a deeper question indeed.
   Or perhaps it's not.

   What it means to be human:
   It gives me a sense of identity and purpose.

   But... purpose? There's the tougher part.