Yeah, RPGs as we know them on video game systems were started by Dragon Warrior, and it does my heart good to see someone else familiar with the game Adventure for Atari.
The first computer RPGs, though, were indeed text-based games as someone stated earlier. Zork was among the leading examples of this type of game.
But if you want the first RPG ever, that's a little bit more difficult to determine. Dungeons and Dragons was released in the early 70's, I believe, though I would be hesitant to state it was the first RPG ever.