Decades ago, someone told about a recent party at which the guests played some new party game. (At least it was new to the listeners at the time.) "It was so embarassing," she said; "we had so much fun."
To all appearances, she thought that party was a wonderful time, something to be repeated. In my experience, being embarassed makes me feel isolated. I made a mental note not to attend any parties with this person.
We spend a lot of time and mental attention noticing how isolated we each are from the rest of humanity and finding ways to alleviate that sensation. One problem seems to be that a technique which works for one fails utterly for another not only fails, but makes the difference and isolation all the more apparent.
A different example: Singing "Happy Birthday". I know that I'm an outlier on this one, but it has always been true that singing "Happy Birthday" makes me feel silly and more separated from the group. It's worst when it is my birthday but it is the same feeling whenever the custom is observed. (You'd think at my birthday people would defer to my sense of what is most enjoyable, but it is hard for them to escape their own experiences to empathize with mine.)
I'm not proposing to spend this space exploring just why it is that party games and familiar songs work against their raison d'etat when I am in the mix. My point is limited to this: In actual reality we are all separated from each other in different ways.
That we are each different is a truism; that we are differently different is a little more significant. Feeling separated from others is an experience we have in common, but only just barely. We feel different kinds of separation at different times in different ways for different reasons. There is no universal angst.