Here's why:
* Common nouns are general names for people, places, things, or ideas. They are not capitalized unless they are at the beginning of a sentence or part of a title.
* Proper nouns are specific names of people, places, or things. They are always capitalized.
For example:
* Community (common noun) refers to a group of people living in the same place or having a shared interest.
* The City of London (proper noun) is the specific name of a city.
So, while you might talk about "the community" in a specific place, the word "community" itself is not a proper noun.