Gotta keep the traditions going

Well, not quite. More correctly would be that a bunch of natives died before the first Thanksgiving. The first Thanksgiving was most likely only possible because of an epidemic that killed many natives prior the Pilgrims arrival. It was that epidemic that made the natives fear the white man's "God" and was likely why they welcomed them with peace and taught them how to plant and hunt certain local wildlife. But don't take my word for it:
http://inthepastlane.com/of-plague-and-pilgrims-how-a-devastating-epidemic-shaped-the-first-thanksgiving-nov-18-2012/
https://www.cnn.com/2019/11/25/health/pilgrim-survival-disease-conversation-wellness/index.html
https://slate.com/technology/2012/11/leptospirosis-and-pilgrims-the-wampanoag-may-have-been-killed-off-by-an-infectious-disease.html