Why don’t we, as passengers, feel the speed of a plane whilst it is flying?

Question

Also why aren’t we constantly sucked back into our chairs like when u accelerate in a car quickly?

In:

Answer 1

At the start, when a plane is taking off that is pretty much what happens. But when you are at a constant speed, or the acceleration reduces then you don’t feel anything.

It’s like in a lift/elevator, you just feel the acceleration and deceleration.