She was trying to get back the chakra that she stole.
She didn't steal anything...she ate a piece of fruit
OT: OP is right. The problem is, like ^buddy above, people still haven't realized that the tree was just a tree until Kaguya merged with it. The tree was just a tree...with a fruit full of chakra. That chakra manifested itself in different abilities after it was spread throughout NV. There was no Rinnesharingan on the tree when she ate the fruit. The chakra brought out the Rinnesharingan IN HER. Then, she merged with the tree, and became the juubi. The juubi=Kaguya. The manga tells you that if you pay attention.
Just like chakra brought out the KKG in other ninja. That's the reason you have "
bloodline" limits. Chakra is just that, chakra. It is chakra+your blood that brings out special abilities. If the chakra fruit from the tree=Rinnegan then that would mean everyone in NV would have potential for Rinnegan since their all using the chakra from the same source :kk:
That's the reason only Otsutsuki members or trasmigrants have been able to get the Rinnegan. You need the chakra from that specific bloodline to access it.
Juubi or Kaguya is the same
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-Kaguya Rabbit Juubi form.
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-Pokemon form.
Kaguya was like an Incredible Hulk can change size
Exactly. Kaguya+holy tree=juubi. The holy tree in itself was just chakra. Once it mixed with Kaguya, the Rinnesharingan was born. Once Kaguya merged with the tree, then we see the juubi with the Rinnesharingan. Rinnesharingan was always in Kaguya's genes, the chakra from the tree brought it out. Read above