Most holidays are done as either a reminder of something/someone important or they naturally occur through habit.
Christmas, for example, is derived from multiple winter holidays. Those winter holidays usually occurred because people would always gather together, harvest all the crops they could take in, have a big feast, and get ready to hunker down for the winter months.
Spring holidays like Easter are the opposite of Christmas. Winter has melted away, Spring has returned, and it's a celebration of renewal and fertility.
Then you've got your historical holidays like Hannukah, which is meant to remind the Jewish people of a horrible time their ancestors endured and survived.
Kwanzaa is basically "Why can't we have our own holiday that looks like a broken down version of Hannukah?" It didn't naturally occur. It's filled with vague platitudes and virtues without directly addressing anything in the black community. It's very manufactured, and it was manufactured recently enough for us to still see the label printed on it.