There are many posts on this site about the appropriate responses to the question "How are you?" and there are many different opinions about which responses should be used. My intention is not to bring that question up here.
My question is about the evolution of the expression "I'm good". I hear it used in two ways all the time. One is in answer to the question "How are you?"
The other way it's used is to mean, "No thanks, I have enough," or "I'm all set here." For example: "Would you like more ice cream?" "No thanks. I'm good." Or this: "Did everybody understand my explanation?" "Yes, I'm good." It's also used in the same way in questions. A waiter might arrive at a table and say, "Are you good?" to people who appear to have finished eating, as a way of asking whether it's OK to take away their plates.
We moved from the United States to France in 1988 and stayed there until 2002, when we returned. Before we left, I never, ever heard anyone say "I am good" in either of those two contexts. When we came back, the expression was everywhere. So I've always assumed that it emerged during the 1990s or, at the latest, around the year 2000. I've also always (perhaps erroneously) assumed that both types of usage evolved around the same time. Many of the posts on this site refer to "I'm good" as an expression used only in American English, but recently I have heard it used by many speakers of British English as well.
I've checked various sources to find the expression's origin. There are a few ideas about it here, here, and here. In the last of the sites I've referenced (wiktionary.org), there are people in a chat room who agree roughly with my estimate of when the expression entered common usage, and one of them suggests that it comes from language used by poker players.
I'm very interested to know if anyone has found more authoritative information about the origin and evolution of the expression, as used in the ways I've described.