I've been shocked by 120 volts AC many times in my life. Sometimes you think a circuit is deenergized, but it turns out its not.
Never pleasant, startles you, but not lethal. You let go pretty quick.
Friend of mine came in contact with 347 volts AC. It really rattled him good, but he was ok.
My understanding is that if the current gets to your heart, it can kill you because our natural pacemaker controls the heart with electricity. If you interrupt that, you could likely die. Your skin has electrical resistance to it, but if your skin is compromised somehow, and you come in contact with electricity, you could die. That's why when they executed people with the electric chair, they wet the skin and they give the electricity a path through you body by hooking up electrodes to your head and your ankles. Plus the high voltage and well, you know the rest.