Witchbane Orb stops targetting
Stuffy Doll does not target
so the two do not interact
Choosing a player is not targeting him. The Doll damaging the chosen player is also not targeting him. No targeting involved here at all, so hexproof doesn't help.
(Something targets only, if it uses the word "target", either in its text or in the rules for that keyword ability. Aura spells also target.)
Thank you for the help both of you