i think it may be a dream but not about link discovering himself but while he is caught in stasis coz mm happened before tp meaning link must have some how aged so i think mm happened as a dream and during it he forgets abvout his life before
It is possible that there are three timelines, one for each Zelda "category" (Child timeline- SS, Oot, MM, TP [the more serious]/Adult timeline- WW, ST, PH [the more comical]/Other timeline- MC, FS, FSA [the more cartoonish]). For the child timeline, the "dream" could have been Majora's Mask. For the adult timeline, Phantom Hourglass. For the other timeline, it could be Link's Awakening.
That would also explain the appearance of familiar OOT characters in Termina too.
Wikipedia said:Gaiden (外伝?, pronounced [ɡaideɴ]) is a Japanese-language word meaning "side story" or "tale", used to refer to an anecdote or supplementary biography of a person. The use of gaiden is commonly used in popular Japanese fiction to refer to a spin-off (canonical or otherwise) of a previously published work that is neither officially considered a sequel nor a prequel.
[...]The Legend Of Zelda: Majora's Mask was called Zelda Gaiden in its development stages.
Nah, the familiar OoT characters were simply reused to save time and resources; Majora's Mask was made within a year's time, far less than it takes to make the typical, 3D Zelda game. Nintendo thought it'd be a good idea to come up with a reason behind the similar characters, and what they came up with is the concept of Termina being an alternate dimension entirely separated from Hyrule. Some fans consider this to be a "copped-out" idea, but it makes sense to me, especially considering the time constraints they must have been under and other various factors. I don't do this often, but I can assure you that there's nothing more to the similar characters than that.
My biggest problem in this theory is that you say he goes to termina to discover his true self after switching between different forms, but what about the transformation masks?
How does ↑ serve to disprove the OP's theory?
Anyway... Finding Navi was Link's main objective, but him being sidetracked didn't interfere with that objective. It is hinted that he continued on his search for her after his quest wrapped up, but, in Nintendo fashion, the details behind this were left incredibly vague. You are right, however, that Majora's Mask is a sidequest, as it was originally to be called Zelda Gaiden. The word "gaiden" roughly translates to "sidestory."