Humans think that gravity is a simple, singular force, but gravity has many aspects and varies depending on the composition of the objects in question and their distance from each other.
Gravity differs between objects of different compositions. Like compositions attract each other more, due to the compatibility of their makeup. They have no extraneous dramas to resolve. Metals figure heavily in this, no pun intended, as a magnetic component enters into the equation. Where there is flexibility for the objects to turn, one or both will maneuver such that they are magnetically aligned. This takes time, however slight, and thus an iron ball may appear to fall more slowly in a vacuum than an object of comparable weight that has but a slight magnetic retention. Organic compounds also react to gravity in a different manner than in-organic compounds, and this is due to the complex bonding between the atoms. Bonding involves tying up the electrons, which are used as glue in that they are shared by more than one atom. Thus, organic material in general will not experience the interference that matter with free electrons does during a gravity attraction. Inorganic material in essence takes time out to shed or take on electrons, slowing its movement.
In general, the heavier an object, the greater the gravity force generated within it for another object. The gravity force is more than compounded, equivocally, but this fact is lost by those viewing the drama because most of the drama takes place within the object itself. Why would this not be the case? Why would matter only reach out to matter not contiguous, with its attraction, and not matter near at hand? Some call this internal gravity compression, but this is merely gravity working to pull each atom toward the greater bulk, which in the case of an orb, like a Sun or planet, is generally toward the center. As the force of gravity reaches in all directions, the larger or heavier object is emitting more of a come-on than a smaller or lighter object. When several objects are involved in giving each other the come-on, the contention causes all of the bodies to dither, but an equilibrium is established in accordance with the mass and composition of the objects and their distance from each other. Humans find their understanding of gravity to be incomplete because they are not taking into consideration the repulsion force that large bodies, such as planets, generate toward each other.