I tried learning a new role not long ago but it just ended in frustration and less fun as I was getting flamed constantly (wasn't even doing bd, just didn't get 7 billion kills).
It is hard to learn a new role as of late so it's hard to say. I love ranked...but I hate it so so much as it ends up being frustrating more often than fun due to other players. I own all the champs so I don't have that to strive for anymore (been playing since 2011). I don't know any rl that plays or wants to play (some have tried and quit rather fast). URF was really a fun thing for me but that went away sadly.
I really love this game but I just feel like I've done a lot and gotten a lot out of it but I stick around sometimes simply because I have put a lot into it and not just because I want to as sad as that is to finally admit. I'm usually good at finding my own fun and not expecting a game to throw it at me, unfortunately it is harder to find the fun in LoL after all these years, especially when all the champions I really loved playing are just weak compared to the newer ones.
My favs were always Karthus, Morg (mid thought I play her support), Sona who is getting ruined currently on the PBE, Mord who is okay, Ashe who is kind of in a bad place in comparison to so many other ADCs, Cass, and really these champs don't fit in quite as well anymore and it makes me feel out of place if that makes sense.
Wish I knew how to make the game fun for myself again but I'm too old age wise to have any chance of getting into the LCS regardless of how good I ever get in ranked and I've been playing too long to find a challenge in normals and normal game modes.