Honestly just takes time. First i was old old ryze they continue to rework him so thats why i stopped. Then it was Heim. Then ziggs for a long time. Then Swain. recently Jax and Currently corki. Sometimes i just get tired or getting instagibbed as ziggs since he is pretty immobile no matter how far back I play because team refuses to ward... So i gravitated top lane with swain so i could 1 v 3 ppl top and still be fine. So naturally after not being able to take towers in low elo that is how you climb. If you want 70% or more. Stick with an AD or auto based champ, learn wave management and take towers > kills. So now I got corki, tried him out. And with triforce, long range poke and escape he fits everything i love about a champ except enough health to not get one shot.
The point is you fall in love with a champ. But the honeymoon phase ends, or riot changes them into something heavily nerfed or different. See riot is about to rework swain, who has been my main go to tanky mage to survive all the crappy low elo assassins and make them useless. They are removing his drain tank. So I gotta move on and premtively getting very good at corki and jax. Next ill try Riven. Trying new roles and new mains has helped a lot with learning macro, wave management and damage output. One tricks are worse at the game overall but just really good at one thing. So be a polygamist or just an unfaithful lover and slowly branch out to try new things, and learn more about other champs.