fault current through a person
The current DOES return to the source. Current has to flow in a closed loop It will come 'out' of the ground back to the bottom connection of your 10V source. I have annotated your bottom picture. Thus the return path will again have 1/3 + 1/3 = 2/3 Amps.



If the 1/3 Amp going through your body would somehow 'disappear' into the ground the source would have 2/3 Amps leaving at the top and 1/3 Amp returning at the bottom. This is not possible.