it's hard to say that someone is a good or bad player. i mean how do you classify that. everyone is where they're at and we're all learning/progressing.
you shouldn't just rely on one champ to be a better player. i play all the champs at least once so that i learn their ranges and their kit so i can best avoid them. i mean, how do you learn to avoid the blitz pull? you play blitz, then you learn his range really well. makes him easier to dodge.
same thing with jinx. how do you learn to do better with jinx? you acquire at least a passing understanding of all the players that jinx is likely to lane against. then you can properly take advantage of them.
with adc's there's only so much you can do. i mean you can have perfect positioning, mechanics and cs flawlessly and win your lane. but if you have no tank line, you'll probably get murdered first in a team fight and that's it.
as a player the best thing you can do is play. play a lot. play every position. get comfortable with multiple champs in every role/lane etc. be as flexible on your acquired champs as possible. at a certain point it's just experience.