I'm not entirely sure what you're saying, but I'm saying that there were, I don't know, loads of princesses we don't see. The Hyrule history takes place over many centuries, correct? Meaning there's more than just the princesses we see. Far more. So, out of about... Probably well over 50 princesses, a few were named Zelda. That was until the particular SZ took place, and ALL princesses were named Zelda after that.
Yes, but it's a pretty major coincidence that every time the hero appeared, the present princess just happened to be one called Zelda, without some explanation - i.e. the SZ story. It's not absolutely vital the SZ appears very early on, but if it can it's better than appearing later. We have no canon evidence of any first born princess of the royal family not being called Zelda, except for Tetra - and clearly, by that time the prince's decree has been forgotten. Except by the King of Red Lions - which means that SZ must come in the same timeline as TWW, and before it, or he wouldn't call Tetra Zelda.
Ganon's just a nickname for Ganondorf. He could be different people, but then there's the similarity of the name. We know he can be resurrected from AoL and Oracles. And the ancient demon reborn line in FSA - but then they could just mean that he's like the previous Ganondorf, I suppose. My timeline would have three different Ganondorfs, I suppose... One from IW-ALttP, one from FSA-LoZ/OoX and one from OoT-TWW.