Champion pool issue
So not sure if this goes here, tips or tricks, or somewhere else, but hopefully I'm not far off. I started maining one champ that I really enjoyed enough to learn and practice on in an attempt to climb ladder. So far I've gone from b3-s5 pretty quick because I kept working on my play, but my champion pool is limited in terms of what I've practiced, and if I keep playing this way I know I'll hold my team back if I ever do make it to a higher MMR.
I've been playing a bunch of random stuff in addition to Heimer lately just to get some variation in since I hit s5 and can't drop right now, but if I'm honest then what I would be playing if I really wanted to climb as fast as possible right now would be Heimer mid/top, Nunu Jg, Janna support, and No ADC...... you want to climb, don't do it, don't offer to fill ADC just to practice it. Gotta change this up and learn some new stuff I enjoy, but was hoping for some input.
I was hoping to pick up something that can go in multiple roles so I can spam them easier and learn in depth. First thought was morg since she can go mid/top/support, but don't know how much she can bully or that I'm good at diving in to use her utility right since she isn't tanky. Other strong considerations are lux/zyra for mid/support (utility and poke to bully with), and Maokai, Zac, Hec, or shy for top/jg options since they all are tanky and can just dive in and cause trouble. I'm also drawn to ziggs for some reason. Poke with a little utility and a ton of aoe damage, but not sure he fits what I'm any good at.
Thoughts, advice and suggestions greatly appreciated.