Societies are naturally diverse and its easy to see why it is.
Interests: Some people prefer to stay inside and use a lot of electronic devices. While others prefer nature and the outdoors, so they go hiking an camping.
Beliefs: This is an easy example, the united states has many churches with many religions, so the belief systems are different.
Age: Even in your house, age diversity is present! You might be 15 while your parents are 35, and your grand parents are 73! This a common form of age diversity.
Hope I helped. :)