Kaguya folktale based theory jamboree happy fun times -GO !!!
I chanced upon this while googling Kaguya and another word which I can't even remember now.
Turns out Kaguya is based on an ancient Japanese folk tale, like so many other things in Naruto. So in honor of the guy who correctly predicted Susano'o, before Itachi Vs Sasuke, I was thinking of starting a theory thread to see what theories folks here can come up with after reading this folk tale. Before Kishimoto eventually reveals the missing details about her past
As far as my thoughts after reading the wikipedia page is that there are varying versions of this story that have been told but it did mention that one version has her sent to earth by her parents to keep her safe from a celestial war being fought which sounds eerily close to what's been said so far about her past. One thing consistent to all the versions is the ending where she must eventually return to her home Tsuki-no-Miyako (lit. "the Capital of the Moon", leaving the emperor and her foster parents in tears. Another interesting parallel I noticed was the folktale Kaguya was said to have an otherworldly beauty, such that 5 princes attempted the impossible tasks she set as conditions for her hand in marriage. The emperor himself was also attracted to her in a big way.
So at the very least the far away land she is from is almost certainly a different planet given that the moon was made by one of her sons to seal the juubi's body and she can already access worlds that are really far away. I think this bolsters a theory that has been rumbling around in my mind lately. Whereby her intentions are to return her homeworld and to use the chakra that she takes from Naruto's world and use it to end the war in her homeland. Further more Black Zetsu, her "child", I believe is the corrupting influence of the shinju, he may be the reason why the chakra fruit was forbidden in the first place. I suspect his motive like with Madara is to further the interests of the shinju. In this case by having Kaguya soak up every last drop of chakra and use it to warp to Kaguya's homeworld so that the shinju can eat up the life energy of Kaguya's people and whoever they are fighting. Essentially a larger scale version of Madara's plan to secure world peace by neutralising each and every last being by fusing all chakra into one.
I've got a feeling the shinju stuff is from a different folk tale which I'll look up sometime soon.