It's good that you feel stupid. That means you realize that there's room for you to improve and that you are surrounded by people who are smarter than you.

That's much better situation than if you feel smarter than everyone around you. There's a famous saying, "If you are smarter than everyone in the room, you are probably in the wrong room."

It's totally normal to feel like that as you enter the real world.

For me, I kicked everyone ass in High School. Got humbled the first semester in college. Got humbled further in grad school. And when I entered the workforce, I felt that everyone was so amazingly good and technically stronger than me. I realize this is a good thing and that I need to keep improving.

Keep grinding!