There was a thread some years ago about the earliest use of the phrase "human being":
I found a citation that is earlier than any of those mentioned. Having no "reputation" here, I can't comment or answer on that thread, but apparently I can post my answer as a question. There is a use of the phrase in Richard Hooker's 1590 "Ecclesiastical Polity" vol. 5. It is quoted in Samuel Johnson's dictionary, to illustrate the word "unapprehended".