You are rignt. As long as Fh = k x and Fs = -k x, the sum of the
forces = 0 and the mass DOES NOT accelerate. Try it yourself.
Pull on the mass until the spring is stretched a bit. Let the mass
rest for 10s.You know that the only way you can get the mass moving
is to apply a little MORE force with your hand. Better yet, put a
force sensor between the hand and the mass. Plot the force.