I am very much a fan of this theory and makes a good point in the forms that Calamity Ganon appeared in being mirrored from Wind Waker.
So a banished half-dead Ganondorf was the source of all the malice which took form as Clamity Ganon. I hope we explore further where this Ganondorf came from but it has its parallels to Twilight Princess with the spot in his stomach where he got executed.
It feels like Nintendo wants to merge all timelines into one with BotW 1+2
Makes sense to me. It's like Ganon, assuming that corpse is Ganon, is looking at Zelda to say "Did you think you were truly rid of me?!!".
Ganon is the pigform and the force that reincarnates into Ganondorf that is the Gerudo humanlike form.