If tu remember, this season we saw Jacob and the man in black's childhood. during that episode, tu see that there was a shipwreck of people a looooooong time hace and they made a society on the island. I believe they were the first.
Well...Jacob's and Black's stepmother dicho that she was from her mother, so that means that there were people before her. (not clear if they all (those before her) were protecting the light from other people o not, but it doesn't even matters much).