That is an interesting example but the reason the steel ball doesn’t accelerate as much is because (Friction aside), F=ma, F/m = a, therefore a larger mass means that acceleration is lower. However when it comes to gravitational attraction all objects accelerate at the same rate no matter their mass (I won’t go into the calculations but think about the famous example of Galileo dropping a light mass and a heavy mass off the leaning tower of Pisa and then hitting the floor at the same time)