I just touched the 230 volt outlet of an Isolated UPS's standing on bare feet on carpet floor. Nothing happened. (Although the mains tester did glow)The earth is a conductor, therefore it acts as a capacitor just like any other conducting sphere.
The capacitance is a lot smaller than you might think, of the order of 700 microfarads. You can go to any electronics store and buy a capacitor an inch long which has a much higher capacitance than the whole earth, but at mains frequency of 50 or 60 Hz, the impedance of the earth is about 4 or 5 ohms.
So if you connect even 100V AC mains to "earth" you wll get a current of about 20 or 25 amps, which is 1000 times bigger than it takes to kill a human.