I didn't know that "people" was plural for "person," and I actually thought it meant grown-ups. (Possibly because we would always be in big groups of people who are mostly adults)
A childhood belief about speaking

others believed things like this
- I used to think that "cross-eyed" meant that people had X's for eyes, like dead people in cartoons.— Tim
- I used to believe that Alexander Graham Bell was not just one person. I thought that they were three people!— J.D.
- when i was little, i thought that a con artist was a person that painted pictures of people commiting crimes— kimkim
- I used to think that only grown ups were "people".Children to me were no people ,they were just children.— Minny
- i used to believe that sex meant love and that having sex meant the two people would live happily ever after.— amy
- I used to believe that only 'poor' people had to go to the bathroom, that 'rich' people didn't.Anon