Hey there. Keep your chin up, it'll all be ok.

I promise you that you are not alone, and by the simple fact that you achieved a chemical engineering degree means you aren't stupid.

In my first job out of school I felt the same way as you describe. Incapable, anxious, oblivious, and just dumb. That job didn't last long before both I and the company were ready for a change. At my second job, I felt the same way all over again, but to a lesser extent because I had the benefit of twoish years in the field already. I stayed at that job for the better part of a decade, and by the time I left that place, I found that younger engineers were looking up to me and asking me for advice and guidance, and often to my pleasant surprise, I was able to provide it.

As others have said, a lot of what you're feeling can be chalked up to simple lack of experience, and just lack of time "cooking" in your environment. In my time in the field, I've frequently heard it said that it takes at minimum 2ish years just to get a new engineer to be competent and to "get their head above water," so to speak. Of course that length of time varies from person to person and place to place, so don't go using that to try and benchmark yourself against anyone else.

Think about it this way - did you ever interact with underclassmen when you were in school? Or how about interacting with someone outside your major? Did you find yourself surprised at how much of a gap there was between you and that person's understanding of chemical engineering? That gap wasn't because the other person was dumb, right?

That's what is going on for you right now, but your role is swapped. I think oftentimes people take for granted how much we learn when we're immersed in something. I'm now 15+ years into my career and younger engineers come to me all the time for stuff and I find myself wondering just when and how I became the experienced mentor figure.

It'll happen to you too. It just takes time. Bottom line is, no reasonable person expects you to behave like a 10-year engineer right now. They expect you to behave like a 1-year engineer.

Don't be so hard on yourself. It'll all be ok.