Well, a normal person is a person who conforms to the norms and standards of the society that person lives in. It is most likely not an extraordinary person and shows only the most common behaviour which is seen as normal by said society. Furthermore one might say that the actions of normal - you may also call them average - persons are foreseeable. I would consider a society consisting of normal and normal only people as a boring society unable to bring forward great innovations or astounding creativity. A functioning and diversified society needs people who stand out. Otherwise it comes to a grinding halt and will not develop.