I worked 31 years in an electronic factory. Yes, 12 volts can hurt. It is the current through your body that hurts. In fact, under optimum conditions, as low as 20 milliamps can kill you. That approximate figure is standard in all safety manuals.
Clean, dry skin has high resistance. Under a metal watch band or a ring can be VERY LOW resistance. Electronic techs are very curious people, and some years ago, we actually did some skin resistance measurements after a safety talk. After this many years, I obviously can’t clearly remember, but we had some measurements that were in single digit ohms on men who wore wedding rings all the time.
If you have a wedding ring, slip it up a bit and see the difference in the skin there and on other fingers. If the ring hits the voltage, that ring has very wide contact with the low resistance part of the finger.
Look up parallel resistances, and you will see a ring is like having many, almost infinite, parallel contacts with your finger, instead of only one where you touch that 12 volts terminal at one point. Ditto with a metal watch band.
That is why I have not worn a wedding ring since around 1968. It’s not worth the risk, and even when I retired, I will never wear one, perhaps from lifetime habit.