What exactly is "normal" and why?

[Master_of_the_Faster]

What do people in society view as "normal" and why? I mean we have the same jobs (some of us), same hobbies, certain religions (some of us), same body functions such as eating and breathing, and other characteristics. Not to mention the environment, diseases that spread, human conflicts, and death. Is this the way life is meant to be for ever? Why do some people just come to the conclusion that they can live life the way they do and consider it "normal"? Also, isn't there more than having the same jobs that people have had in the past or present (or jobs similar to that in these times)? I just want to hear from everyone else before I might say something (because I can't think of anything right now unless someone brings up a good point).