It always tickles me people would say they know a gay guy that he loves 100 miles away and ask if I knew him.. people think that we as a gay community we know each other by telepathy .. so I’d ask them if they knew every straight guy out there just to sound as stupid as they do
...since there are fewer gay men on earth than straights, you response is not completely correct, however i can relate to the frustration that comes with such questions.
And as winesthel945 already pointed out, the (small) community of gays connects a lot over several cities, country or even continents. At least some of them do.
I experienced this in my town too. Whenever we meet "new" people we quickly find a connection to to them over people we already know.
However, let me tell you that most of the time they don't always really "know" each other. It's often a friend of a friend of a friend of a friend of a boyfriend's cousin. So sure they know names and may have hook up, but appart from that they may not really speak to each other.
In my experience it may feel like you are coming into a huge group of friends in the beginning and the more you explore that group, the more you realise that the actual clique is only half as big as you thought and there are people like you present who feel just as much as an outsider as you do.
The social media issue is a whole different thing.
You may not look like "the people on Instagram or Twitter" but the truth is, nobody does. Not only is instagram famous for filters but people of course only share pictures of them, when they are doing something fun. Or even when they are just chilling with friends, a lot of people assume some kind of pose they think they look best in on a photo.
The societal standards of what is beautiful and worthy to be a goal do the rest.
Lastly, there might be people like you out there, who just do not use social media as much and might not attend gay events.
Take me as an example. I don't use twitter nor insta and even in here i "hide" behind a delicious photo of somebody else.
All in all, don't feel itimidated! Their "bond" might be weaker than you think and not everybody uses social media. You are just presented with the loudest of the crowd first.