Earth attracts each and every body with gravitational force. A freely falling body is continuously accelerated because gravitational force is continuously acting on it. Gravitational force on a falling body is proportional to the body's mass. Hence feather and boulder falls with same acceleration according to this formula g = f/m. Hence g = 9.8 m/s^2 is a constant near the surface of the earth.
The g depends on the mass of the celestial body. g is small on the moon. So jumping will be very easy on the moon. g is greater on Jupiter. So even walking will be difficult on it