I've improved so much, not by any increased thumb skill, but by playing smarter. Granted a lot of that is experience, knowing how to react to certain situations.
Even aside from smarts or experience, it's about mindfulness. You don't need to know the TTK's or the perks for each gun in the meta. You don't need 1300 hours played. Just a little awareness as you play. Now, in a game with Kill Times at about ~1 second, it's hard to actually find awareness. But you'd be amazed how often you die when you take a fight where you've already lost your shields or you ran head first into a shotgunner because you weren't paying attention to engagement distances. If I asked you now if you'd do that, you'd say of course not! Finding that mindfulness in game is hard, but will up your game so much. Or at least it has mine.
So as you play, ask yourself what you're doing right now.