Leaving aside the discussion about privilege, if you go back far enough, any commonly used term/idea will be entirely unused. For any term, there's someone who used it first, and for some of those terms we can identify who that person was, and some of those people are responsible for popularizing the term in question.

It's one thing to say that we don't know who coined the term "privilege" in the context being discussed, but to dismiss the possibility of knowing who coined any common term is just clearly false.