Without air resistance, all objects in free-fall on earth accelerate downwards at 9.81m/s2.
Yet, all objects have different Fs values...
how does it make sense for different ojects to have different foces of gravity and yet to all have the same acceleration of 9.81m/s2?

Recall Newton's Law: F = ma. Or rewriiten as: a = F/m. This says that an object's acceleration is equal to the force applied to it divided by its mass. Under gravity an object of mass m feels a force downward equal to F=mg. So, if you substitute F=mg ino a = F/m you get a = g. Hence all objects under earth's gravity at the earth's surface accelerate at the rate g = 9.8 m/s^2.