By arguing there are no necessary conditions you are essentially saying we can't use mathematics to describe nature and there are no laws of physics.
For it to fall from the tree? Well, that's a linguistic trick; for it to fall from the tree it must have been hanging on the tree, so that necessary condition is actually a tautology.
Physics describes a world with statistical regularities, not absolute laws. Even a clockwork Newtonian universe is not time-reversible; it has multiple pasts that can lead to the observed present.
E. g. "The apple hit Newton on the head" could be explained by:
1. The apple was hanging on the tree at `t - 1` and the wind shook it loose.
2. The apple was flying through the air because his mother threw it and it collided with his head
3. The apple spontaneously generated due to as-yet-not-understood quantum fluctuations 3 meters above his head.
Something to be a necessary condition has nothing to do with time-reversibility, it simply states a logical relationship
Let me give you another example: To accelerate a body with mass m it is necessary to exert a force onto it. All mathematical descriptions In fact equivalency, requires conditions to be necessary and sufficient.
Your argument that physics describes a world with statistical regularities is a maybe a nice philosophy, however most physicists (and regular people) do not believe we live in a simulation, but physical laws describe the real world.