Bull*navi* it's an "origin story". Why? Because what's it the origin of? THAT dang cap, not ALL dang caps. If you could miraculously prove that there was ONLY one green cap throughout the entire history of the Zelda series, then it is an origin story because the cap was created... and every other game depends upon it. However, just because X is created doesn't mean it's an origin story when there can (much less, there likely are) multiply copies or creations of similar or substitutive Xs.