Question

I know that earth is spinning very fast but why don't we fell  it spinning ?

Answer 1

Because were inside the earth and when the earth is spinning if you look in the sky you will slowly see the clouds moving but were inside the earth so you can't feel the earth moving

Answer 2

We never feel motion. What we feel is CHANGE in motion ... when either speed
or direction changes. That's why it's so easy to fall asleep on an airliner cruising
at a steady 500 miles an hour.

On the Earth, the speed doesn't change at all. The direction does change, because the Earth is spinning and your motion on it forms a circle every day.
But it takes 24 hours to describe a full circle of 360 degrees, so the direction
of your motion is changing only about 1/4 degree per minute, and that's not
enough to feel.