Which is why it's sometimes stated as "Entities should not be multiplied unnecessarily" - i.e pick the explanation with the fewest moving parts. That's less subjective, assuming you can agree on how to count the entities.

1. Things always fall down

This is not actually an explanation at all, it just restates the observation.

2. There exists gravitational force between bodies

Newton's inverse square law of gravitation is simpler than relativity, and it's good enough for a lot of uses. But it is not a viable explanation either, since it does not fit exactly with observed reality - it does not handle the edge cases of very fast or very heavy stuff.