True, but having a lot more of one definitely does make a difference.
See here for more information on static electricity, for example. It's common for a person to have several thousand volts of static electricity built up on them. Even a small static spark discharges hundreds of volts. But, static discharges of this kind have very little current.
Compare that to an arc welder, which typically operates at only 15-30 volts. With one hundred amps or more, that spark is very different from a static spark of hundreds of volts.
Also, from here:
It's not the voltage but the current that kills. People have been killed by 100 volts AC in the home and with as little as 42 volts DC. The real measure of a shock's intensity lies in the amount of current (in milliamperes) forced through the body. Any electrical device used on a house wiring circuit can, under certain conditions, transmit a fatal amount of current.Currents between 100 and 200 milliamperes (0.1 ampere and 0.2 ampere) are fatal.
Just got out my VOM
Measured resistance between thumb and index fingers.
Came up with about 500K Ohms.
The harder you squeese the probes the less the resistance.
Wet fingers and even less.
If I remember correctly your figures of 100 - 200 milliamps being a lethal amount of current is correct.
All ya have to do is a bit of Ohms Law.