Secret of Mana wasn't really an RPG.. but it could be one, but in my opinion, RPG is when you command the character what to do, instead of running around and slashing monsters as you go just like Zelda. But Secret of Mana was a pretty good game, but never got half way through the game lol.
when you think so about real time combat and rpgs then there are many rpgs that are no rpgs for example diablo 2 and i belive that there are "some" people who say that this is a rpg. (me included)