Ten Tails: Is It A Ripoff? The Verdict Is In.

The only way the 2 explanations could possibly fit with each other is if kaguya did bring an existing ten tails, it grew a decent chakra fruit somehow without an otsutsuki sacrifice, and it morphing back into a ten tails was just an anomaly after kaguya merged with the tree. It is regarded as the progenitor of chakra, and is tied to the legend of the sage of six paths and the birth of shinobi. First appearing in naruto vol. I think when obito becomes the jinchuuriki, the ten tails was still just the ten tails for the most part. The latter having eaten its chakra fruit and later merged with the god tree in a battle against her sons, hagoromo and hamura.