Sorry for the delayed response. Busy weekend.
Anywho, Majora's Mask originality is unrivaled in the Zelda series. But, that creates an oddball game that isn't a definitive representative of the Zelda franchise.
We do not live in a hypothetical world. Refrain from using "what if's". Facts are all that matter. The fact is Ocarina came first.
Another fun fact: Miyamoto, Zelda's creator himself, had very little involvement with Majora. And having Ganon and Zelda absent makes the hero of time's presence in-game a bit odd.