What exactly is Madara implying about the Sage of Six Paths? Since Chapter 646 is currently the latest chapter, the question will be in spoilers.


   My question specifically pertains to whether or not all shinobi descended from the Sage of Six Paths. Is this what Madara is implying in the last panel of this picture: "[...] in effect, taught us all chakra..."?

 

 I think there are multiple ways to interpret this. One is that all shinobi are related to Kaguya, meaning everyone related knows how to use chakra.

 And the second way is that if one knows how to use chakra, then all their offspring will be born into the world able to use chakra. Therefore the Sage of Six Paths can simply teach others how to use chakra and then everyone else knows.

 There were probably some words lost in translation, so I am just confused now.

 Did all shinobi descend from the Sage of Six Paths or did the Sage simply just teach others how to use chakra?
At the moment there might not be a definite answer for this question, so here's mine based on my own interpretation of the chapter (with little or no evidence to back up) which might likely become obsolete owing to any twist in plot later on


  Chakra was initially an entity unrelated to humans or their physique until Otsutsuki Kaguya ate the Shinju's fruit and caused the inception of a generation where it would be a part of the human body (as a chakra system). 


Secondly, Otsutsuki Hagoromo aka the Sage of Six Paths, the immediate successor inherited Kaguya's chakra and was likely the root from which the generation of shinobi branched out. 

Further his likely mastery over the Juubi and becoming the first Bijuu could likely be attributed to the real beginning of shinobi who further learn to mix physical energy with chakra to create elemental energy (something perhaps, the Sage might have practised first and preached on to the subsequent generations).


At many points it is also mentioned that the Sage had two sons who later on branched out into Senju and Uchiha. 

However though the Sage might be essentially the first to truly realize the power of chakra, it is very much possible that Otsutsuki Kaguya could have other children who might have inherited the gift of chakra and could have possibly been the root of other shinobi clans.