Why the same plot for every Mario game?

The RPGs: Allow us to introduce ourselves.
Also, Mario Galaxy has probably one of the best intros for a game I've ever seen, Period

The RPGs aren't cannon, you know. (But I agree. Mario Galaxy's intro is so good! :)

They are canon. Miyamoto himself even confirmed it in an interview.

Wait, really? Huh.

Yup. I don't remember where, but I think that it was an interview about BoTW. In that interview, he was asked about Mario, and he confirmed that every Mario (including Mario from Super Mario RPG, Mario from the Mario and Luigi games, and Paper Mario) is 100% the same Mario we all know and love, basically confirming that the RPG games are canon. (As well as confirming the the Party games and Kart Racers are canon too lol)

interesting. IDK how the spinoffs could work tho lol.