It is natural to feel overwhelmed (and borderline stupid) when you are learning something difficult and new. To be honest, this is an indication that you are on the right path.
When you already know something, recall is easy. There is nothing new to build or learn, so there is no strain. Learning is the opposite. Your brain is forming new connections, and that is slow and effortful.
This is why struggling with a new domain, blog, paper, concept, or a new system design pattern feels weird, even when you are making real progress.
When something seems confusing, and you go like, “Wait, I do not get this,” it does not mean you are failing. It just means that the material has not clicked yet and has not become a mental model.
So the next time you are three hours into a new concept, codebase, video, course, whatever, and everything feels foggy, that fog is not proof that you are bad at it. It is proof that you are doing it right, so long as things are becoming easier along the way.
To put this more succinctly, feeling good is what learning feels like after it is done, not while it is happening.