Question

Why don't we directly perceive the motion of the earth, without seeing the movement of stars etc. ?

Answer 1

The answer lies in the nature of Earth's movement. Think of being on an aeroplane when it's smoothly travelling at a constant speed and constant altitude. You've unbuckled your seatbelt to go on a walk down the aisle, but you can't feel the movement of the plane. The reason is simple: you, the plane, and everything else inside it is travelling at the same speed. In order to perceive the movement of the plane, you have to glance at the clouds outside.
so we cant directly percive the motion of earth