1)Simple machines are useful because they reduce effort or extend the ability of people to perform tasks beyond their normal capabilities.
Examples at Home:
analog clock.
bicycle gears.
door hinge.
electric fan.
office chair wheels.
pocket door.
2)The Inclined plane in the human body is the foot. The surface is flat, and slanted and it can hold up your body weight.
Examples of simple machines: A pulley In the human body when the tendon of a skeletal muscle slides over a round, bony surface, the "system" acts like a simple pulley.