Re: stop the "uzumaki" thing...
It doesn't matter to you what he was! All you want, is to believe the Sage was born with a Rinnegan, which is impossible. And now you know your belief is in danger because the Juubi has that eye and it is now obvious he was the progenitor of that eye!
The sage was an Uzumaki who sealed the Juubi within himself, got the Rinnegan, created ninjutsu, had two children who were born with the Sage's powers which were the Juubi's powers, due to him being its jinchuuriki at the time. And thus Senju and Uchiha descended from those children.
Being part of a lineage doesn't mean you are a descendant of that lineage, it could be the other way around as well. Learn your frikking English!
It was mentioned long ago that Uzumaki and Senju are distant blood relatives, and then the Uzumaki were mysteriously wiped out, yes the Uzumaki who specialised in sealing jutsus and were perfect for becoming jinchuurikis.
This guy >_>