One can certainly shock onesself with a battery-powered car starter jump pack, particularly if one is a conductor to the ground or the circuit connects through the heart (which it sounds like anterior-posterior helps with).
Potential Energy charge in a battery wants to return to the ground just the same.
Oh, yeah, you can shock yourself very hard. But between two battery contacts, there is no ground. You can touch either one with no problem. It's when you touch both that you get the blast.
There's no return circuit even with your feet in salt water if you touch only one post of a battery.
I don't think that electron identity is relevant to whether there's e.g. arc discharge between + and - charges of sufficient strength?
Connecting just 1.5V AA battery contacts with steel wool causes fire. But doesn't just connecting the positive terminal of a battery to the ground result in current, regardless of the negative terminal of the battery?
(FWIU that's basically why we're advised to wear a grounding strap when operating on electronics with or without discharged capacitors)
Grounding straps prevent static charges from building up on you. A battery doesn’t really have a ground. The body of cars is hooked to the negative pole of the battery, so it’s called the “ground” of the car, but that’s for corrosion reasons.
Potential Energy charge in a battery wants to return to the ground just the same.