I actually *just* reread this book two days ago - one of my all-time favs.
Meursault is complicated; he'd be a horrible protagonist if he wasn't. Deciding whether or not you think he's a hero will mean that you need to put parameters on what you think being a hero is. Is he a yank-a-man-from-a-burning-building-type hero? I can't really argue that he is. But if you define heroism differently, then he can easily be a "hero".
eNotes has a great mini-analysis of him and some of his inner workings. Camus himself actually spoke of his intentions with Meursault.
I've included three links below directly, and I'm pasting one more in here I think you'll find helpful. All of them will help you get a clearer idea of who Meursault is supposed to be and perhaps what Camus was trying to accomplish. Make sure you brush up on basic existential philosophy, too, if you're still having troubles. Good luck