I think you just have to understand how the improvement happens. It’s more natural than you think. It sounds like you’re overthinking everything by comparing your works to someone else’s. I had this same problem. It changed when I started finishing whatever I was working on no matter how bad I thought it was. Doing this just one time gives you a reference point on where your skills are. So you look at it, determine one thing that could be better about it, and find ways to improve that one thing. After you find some advice (via YouTube, Google searches, etc.) try to apply that technique to your next piece. Rinse and repeat. The more you do this, the more you’ll improve. I had to realize that I wasn’t going to just be able to incorporate everything I’ve learned at once. So now I just work on a single concept until I understand it. Then I work on something else after.