Riot has explained this before, but I'll repeat it for you.
The reason Jinx is always in the meta has nothing to do with her strength compared to other carries. It's simply that she has a niche abuse case and that niche abuse case applies in every game.
Riot designed Jinx to be exceedingly good at destroying turrets, to fit in line with her thematic of being this destructive hyperactive vandal and serial criminal. That's fine. She's incredibly immobile and her team fighting has been brought down to be much more snowbally (need at least one kill to really get those rockets going).
The thing is, in games where you aren't 5v5 and everyone has only text chat to form strategies or communicate, destroying turrets is really the primary use of a marksman. AOE physical damage? We have bruisers and assassins who do it faster and with less counterplay, while also being tankier. Long range poke? That's mid's job. Wave clear? Most meta marksmen have terrible wave clear and rely on Stattik Shiv for that kind of thing, to the point where Riot has to buff Stattik specifically against minions because it is a crutch they acknowledge marksmen have.
Marksmen exist to sit in the back of the team, survive the team fight, and then push and take turrets as quickly as possible afterwards. Jinx has long range, she has a speed boost when she gets kills that allows her to kite, she has some CC that works well with positioning and long range, and most importantly, she can wreck the hell out of some turrets if you leave her alone.
That's why Jinx is always in the meta. Has nothing to do with buffs or nerfs and everything to do with the fact that Jinx is exceedingly good in games where people do not form specific team comps.