Culture
Culture, at its core, might simply be how humans experience themselves and each other. In its broader sense, culture is also everything we do and create, and in its broadest sense, it's everything we have ever done and created and ever will do and create.
In the best interactions with other people we practice new ways of experiencing each other and ourselves, and in the worst interactions we regress into old ways of experiencing each other and ourselves.
It seems to me that in the last decades we haven't made much progress.
If the majority of humanity goes backwards for long enough and we loose our ways of experience, our whole culture will collapse, regardless of the knowledge we have collected.
This is why the simple interaction between two people can be revolutionary, it can be the beginning of a war, the end of a culture, or the birth of a new culture.