TL;DR: All of us have probably been here at some point. Don't get discouraged! There's so much to this game outside of aim, aim is just easy to notice and reflect on (and get discouraged by). You will get substantially better, just keep focusing and building on your fundamentals and you will absolutely get there.
This was me when I joined the team. I'd played a ton of shooters growing up, but the one shooter I had never really gotten into was CS (I'm a big exception from most folks on the team in that regard). The biggest thing I can say is that it's easy to focus on aim as an area of improvement because it's so salient, but every time I felt like I hit a wall where "I just can't aim as well as these players", there was actually something else holding me back. My game sense, my utility usage, my movement and peeking, my general strategy and approach, my crosshair placement, etc.
As I've learned more and more about the game, the more I've come to appreciate that aim is important, but it's a subset of a much larger game. It's just very easy to point out and notice when you're getting shot or losing gunfights, but looking back I realize that I shouldn't have been in so many of those positions in the first place. It gets better!
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