Too dumb for school

So I got my diploma a couple years ago at a community college and just recently decided to go back to school to get my college degree. I got the results of my first exam back and I didn't pass. I got 40% !!!! 😢 I feel so stupid. I was on the dean's list back when I got my diploma and now I'm not even passing. Did I make the wrong choice going back to school?? Am I too dumb for school ??