You're solving for force when the thing that causes the damage is (very rapid) acceleration. The total acceleration comes from the initial difference in speed between the two things that collide and the proportion of the acceleration applied to each object is inversely proportional to their relative masses.

If they have the same mass then they each take half. If one of them is 19 times heavier then the other one takes 95% of the acceleration. If one of them is six hundred trillion times heavier then the other one takes ~100% of the acceleration, but this is still only ~5% more than taking 95%.

Consider what happens if you walk at 2 MPH into a concrete pillar which is fully anchored into the Earth. The mass of the Earth makes the mass of your body look like zero with some zeros after it, so are you immediately crushed? No, but get launched out of a cannon into the pillar at 200 MPH and you're dead even if it's not anchored into the Earth.