communities are complicated, but they do exist. just because you can't define or explain something doesn't mean it's not there. humans have this need to encapsulate everything with words and a concrete definition. it helps us organizing our complex worlds. some people i know say "community" doesn't exist, that it's a catch word that we just use to mean "a group of people" but you can't really say who is part of the community and what it is about the group of people that makes it a community.
i think communities are real. just that it's inherent in the concept of community that you can't explain it- you can't say precisely who is in it, who is not. people in the fat part of the bell curve are obvious community members and the people on the edges are not so obvious. but that doesn't mean it's not real. just because you don't understand something doesn't mean that it doesn't exist. community has the prefix "co," which means "with or together." a community is a group of people who are with each other in some way. people talk about communities of ethnicity, religion, political belief, etc. people also talk about communities that are defined by proximity- like a neighborhood community. none of these things are concretely definable. and that's okay.
there is something that exists within a group of people. a communal identification with one another. maybe this is the important part of community, that there is some sort of collective shared identity. about something. anything.
yeah, it's really confusing.