Uncle G, you wanted to know about Thanksgiving.
Here is a historical article that deals with the myths and gives a more historically neutral viewpoint.
https://fortune.com/2017/11/21/than...why-settlers-really-started-the-annual-feast/
The popular story, that it was started as a celebration to offer thanks to God for a good harvest and peace with the local native American tribes, is at best apocryphal. The part about offering thanks to God is no stretch because the settlers were religiously active, seeking freedom from the oppression of the "official" church of England. That it was related to a good harvest is no particular stretch either. Peace with the local tribes? There, we may have a disconnect.
However, the fact that George Washington acknowledged the existence of the celebration by making an "official" date for it DOES verify that the tradition had been around for a long time even before the USA was founded. It therefore can be claimed as an old tradition. The article verifies a record of the first Thanksgiving feast as of 1621, which is 398 years ago. I think that's long enough to call it a tradition.
Now, what it means in MODERN terms? It is the lead-in to the Christmas season. The day after Thanksgiving here in the USA is called "black Friday" because people start buying their Christmas presents and the merchants hope that the improved sales will put their accounts "in the black" by Dec. 24th. It marks the beginning of huge sales events in any department stores, car dealerships, and a few other businesses.
For our family, it means (or actually, MEANT, since I'm writing this at the end of the day) gathering the family together to eat, swap stories, wish everyone well, and in general gave a gathering for something other than a funeral. It is also a time when many of our churches and other charitable organizations sponsor extra-lush dinners for disadvantaged people - the homeless people of the city, the elderly people, the shut-ins whose mobility keeps them from going very far, ... people like that.