> authenticity is about not trying to fit in, and if he was excluded for not fitting in

You are comparing two things that aren't always equal as if they are. For example, if someone tries not to fit in, thus resulting in not fitting in, they would also not be considered authentic.

Authenticity is graded on why you are trying to be, not on the result you achieve. If you see authenticity in the way you describe you will be lead astray in finding it in people