I'm studying electric potential energy and its defined as the energy needed to move a charge inside an electric field from a point $a$ to $b$. Then, it defines electric potential energy per charge, that is, given a charge, I can know the potential energy at any point of the system.
Now, I was watching a video about a person rubbing its feet on a carpet and getting electrocuted after touching the door's metal. The video says that this happens because the person had a higher electric potential compared to the door.
What is the electric potential in this case? More charge means more electric potential? I can't apply my definition of electric potential for a charged person, because the book defined electric potential energy for a particle far away from the charge source, but the person IS the charge source, how can It have potential at all?
I can, however, imagine lines of same electric potential around the person, but I don't understand how it can have an electric potential at all.