Although your body is a very good conductor of electricity, it does offer some resistance to the flow of current, with the greatest resistance located in the skin. Dry skin is a very poor conductor of electricity. If you flipped the battery back and forth changing polarity very rapidly in the circuits you built above, you would create current in the circuit that would reverse direction each time you reversed the polarity of the battery in the battery holder. This of course is not a very practical way to create alternating current electricity. The amount of current an appliance draws depends on the ability of an appliance to resist electricity.
Resistance depends on the material through which the electricity is passing.
However, the power delivered by the electric company is sufficiently high to be very dangerous to humans. This unfortunate biological coincidence means that nerves in the human body have maximum responsiveness to the ac electricity with a frequency of 60 times a second delivered to our homes by the electric power company. The resistance for the circuit that is completed when a human serves as a conduit for electricity is set by the skin. Dry skin does not conduct electricity very well, and therefore has a high resistance, about 10-100k . Moist skin is a very good electrical conductor, and therefore has a small resistance, closer to 1k .