Use a colon, not a semicolon, before a list. (A semicolon serves two purposes, and only two: to serve as a sort of “super-comma” for separating items in a list when the items themselves contain commas, and to connect two complete sentences that are very closely related.)
When they told me that I was different, I pictured a number of things: super powers, aliens, mutants. But I never imagined that it was my stereotypical normality that made me stick out amidst the crowd.
If this person does stick out compared to everyone else, by definition that means he/she is not ‘stereotypically normal’ in this setting. (Also, stereotypical normality is a damn awkward phrase, not to mention redundant). I know what the writer was trying to say, but this isn’t it. Perhaps ordinary humanity would make more sense.