If any game in which you create stuff is a "creation game," then any game in which you play a role is a role-playing game and any game in which you fight is a fighting game. This is the analogy you missed the point of earlier, and the logical extension of the premise you presented. Your definition of the genre is so reductionist as to render the genre label meaningless.
Broadly, if you're going to label games with genres, ask yourself the following question: "Do I have reason to expect that somebody who enjoys other games in this genre will enjoy the game I'm trying to label with the genre?" As a concept, genres group media that share similar elements, allowing somebody to make predictions about how much enjoyment and what sort of experience to expect by considering their experiences with other examples of the genre.
Somebody who likes SimCity can - based on that example of their tastes - be expected to enjoy Cities: Skylines, Frostpunk, Rimworld, Prison Architect, and other examples of management games that are structured similarly, employ similar game mechanics, and provide similar challenges and goals. Somebody who likes SimCity cannot - based on that example of their tastes - be expected to enjoy Minecraft, as it is not structured similarly, does not employ similar game mechanics, and does not provide similar challenges. As such, labelling them with the same genre based on such fundamental conceptual similarities as "they both involve creating stuff" fails to do what genre labels are supposed to do.