Individuality is what sets us apart from the herd, what distiguishes me from you and them from them. There are two levels of individuality, the first of which is physical. People just plain look different from each other, and at the same time they also dress differently as an expression of the second level, which is mental or internal individuality. Everyone has different thoughts, opinions, and morals which come together to make up who we are. Of course, not every living being is blessed with individuality, so relish what you've got...

For example, here's the world without individuality:

Ant Drone 984954: Hey, other ant! We look the same!
Ant Drone 980739: Yeah, and this damn hive mind isn't helping any!

Not too pretty. Now here's the world with individuality:

Jimmy Joe: Gee ditty, I sure am different than you.
Billy Joe: You sure are, now let's fight about it.