Kaguya Ōtsutsuki

was the first human to possess chakra and is the mother of the Sage of the Six Paths.

Background
During one of the wars of old, Kaguya decided that it was necessary for someone to attain god-like powers in order to stop the war. For this reason, she consumed the fruit from the God Tree, and attained god-like power thus was able to single-handedly put an end to all the wars. Kaguya would later give birth to a son, Hagoromo, who was the first person born with the ability to manipulate chakra. However, the god tree became furious by this and was determined to get its stolen chakra back, and thus become the Ten-Tails. Her son would be the one to later seal the beast within himself and teach the world how to manipulate chakra, becoming revered as the Sage of the Six Paths.