Haha, I feel you. I just got to ranked, but honestly, try out tons of champions, see which ones you're in love with. If it can do multiple roles, go try it out in normals.
My fall-back character (and fave) is Tristana, and I learned how to mid with AP Trist, though it got nerfed now with high cd's. Otherwise, I started out Nidalee Mid (spears OP), and moved on to Tanky Top Nidalee later. Only thing I can't do atm is jungling... fk jungling x.x...
You kinda get the point though. As for being able to play more characters... I'd say stick to the ones you love. I'll be honest, I can't relate to the playstyles of 90% ish of all the champions, but the 10% I can play and the 5% that I absolutely love... I can and will make effort to get better at, even in odd roles.