I’m sorry that you have lived with this negative self perception for so long. Having started out as a child, comparing yourself with those around you, suggests that you have been reinforcing this negative illusion for most of your life. I did the same thing growing up. It took me quite a few adult years before I even began to understand how I was creating the person I did not want to be and in truth, existed only because of my negative self perception.
Virtually everyone I’ve talked to can relate to the “imposter syndrome,” believing themselves to be inadequate, and have only attained their place in life because of some strange fluke. This problem exists in a lot of people, even if they graduate with honors.
That syndrome is like a layer that exists overtop of a deeper layer that formed earlier in childhood, typically as a result of comparing self to others in school. In the classroom jungle, you might be a lion, a gazelle, gorilla or whatever. Each of these animals are comparing their abilities with those of others around them. The lion may feel slow and dumb because the gazelle can outrun him. The gazelle may feel inadequate because it could easily become a meal for the lion. Both of them may feel stupid because the gorilla can learn sign language and talk to people.
In the classroom, you have all these diverse personalities and aptitudes. Sadly, in an attempt to instill conformity, teachers often encourage students to compare themselves with others. Nothing good comes from comparing. Comparing that triggers the ego is likely to erode integrity. Comparing that triggers feelings of inferiority disempowers a person, making it profoundly difficult for that person to sense anything positive about themselves.
Ask me what I learned in college and I’ll struggle to come up with any details. Ask me what I read in a book yesterday, and I’ll have the same problem. I can generalize about what I learned or read, but if challenged to remember something specific, as often as not I won’t be able to. That’s usually how the brain works. It’s not just something that happens to you or me. People usually can’t remember a lot of detail about schooling unless they are presented with a scenario that corresponds to some previous teaching.
I graduated with honors. Ask me something about microbiology, and I’ll probably just be scratching my head and wondering. I think the most important thing about college is learning how to learn and figure things out. If your work draws on past education, it will come back to you.
I can tell by your writing that you are absolutely not stupid. Take an inventory of all the things you have learned and accomplished. Add to that the wisdom and emotional intelligence that you have gained. Those are the facts that will present the reality of who you are. Leave all that comparing stuff behind.