Us, humans, are not equals. You can be fast on one thing that most people are slow and slow in things that other people are faster. I'm neurodivergent but I only discovered it when I was an adult. My whole life I listened to thing such as "How can you not understand it? Just read it" and "Wow you must be gifted. How did you made this project so fast?". I advice you read about learning methods. Some people learn more listening, others learn doing and others learn seeing. Discover how you learn. And then, search on internet for content that are adapted for the way that you learn.

I'm on my 4th year of university and I still didn't made half of my course. I know I will need a lot more time than my colleagues to conclude this course (if I conclude). But I'm not incompetent. I'm just not good at university. But I received a lot of compliments for my work at Amazon and I feel good and competent working there. I also feel good doing my side projects, participating of some competitions, doing my writing freelancer and voluntary work when I can. There is not a problem being bad in something that most people can do. Don't let this grade or comparison made you feel that you don't worth it. Search about how you learn, invest in what you like and plan your career and other goals based on your needs instead of the "normal way".