If we are in an ancestor simulation replicating an early base reality, then I (or an earlier version of me) will have already decided whether to lift my hand or hesitate. It might feel like I am choosing, like I have free will, but it could be my consciousness experiencing my ancestor’s existence, and I am making the same choices as they did previously. It FEELS like free will because when my ancestor experienced it, they did have a choice. I do not.

All of those atoms and particles might be simulated as well, along with he chaos of rain. They may seem to be acting freely, but even their action might be scripted. Heck, the simulation might even be coded at that level. That atom crashing into another may have happened in the past and is being replicated many millions of times over.