Deflecting Palm doesn’t target any creature or player. You choose a source of damage as Deflecting Palm resolves.

If multiple prevention and/or replacement effects are trying to apply to the same damage, the player who would be dealt damage chooses the order in which to apply them. Notably, if noncombat damage would be dealt to you by a source controlled by an opponent, you choose the order in which to apply Deflecting Palm and the planeswalker redirection effect. If you apply Deflecting Palm first, the damage will be prevented (and damage will be dealt to the source’s controller) and the planeswalker redirection effect won’t apply.