Following the end of World War II, a few hundred thousands Holocaust survivors wandered around Europe searching and hoping against hope they'd find some surviving members of their families. Some did, most didn't.
But many of them, as they met other people in the streets who were apparently in the same search, would ask "Amcha?" - that means "Are you of the People?" They wished to know if their interlocutors were Jewish, maybe as a way to compensate for the frustration of not finding survivors from the biological families...
And yet, this idea of "Amcha" is older than the Shoah. How often do we go down a list of names (Nobel laureates, famous authors, movie credits, etc) trying to see whether we can spot a Jewish name? How often do we try to find "the Jewish connection" for what we read and see?
The idea of Jews and Jewish community functioning as some sort of surrogate family goes back centuries, and it is probably rooted in the continuous expulsion from one place or another and being forced to settle someplace else.
The closing acts of "Fiddler on the Roof" provide several examples. As people are leaving Anatevka, the butcher (with whom Tevye, as you recall had a serious run-in) stops by Tevye's house to say good bye, mend bridges, and compare plans. As the butcher mentions he will be going to Chicago, Tevye counters "We will be in New York, also in America, we will be neighbors!". This reflected not only ignorance of geography, but also the anxiety provoked by dislocation. We yearn to see in the new place some familiar faces, some taste of the old "Home"
We are yearning for the sense of family that is no longer there. The more radical the change, the stronger the yearning. It is Human nature. And old joke among American Jews defines "Reshtetlment" as relocating to Florida only to find out that your neighbors are all people from the community you come from.
In the same way that we yearn for familiarity, we yearn for the past. Many times not the real Past, but an idealized one. We look back in time and we see not what it was but what we miss from what it was. Fiddler on the Roof presents an idealized version of the Shtetl, because it is the version we want to remember. If you can ask any of the people who really lived in a Shtetl, they will tell you that the shtetl was poverty, mud and hunger.
That is why when we look forward, we keep trying to rebuild the past as we remember it instead of bulding something new. We prefer what worked in the past rather than the uncertainty of what the future might bring.