Yeah they didn't have Uchiha power you need both Senju and Uchiha to get the Rinnegan thats why i say that Nagato was givin Uchiha power by Madara and mabe the same was done by Itachi to Naruto.niether hashirama nor his brother or tsunade show any sign of ranningan so i dont think it is a KG at all.
And if you don't like it no one put a gun to your head to read this thread there are hundreds more to read.