I always thought the ReDeads were wearing masks. The spooky mask from OOT is the same one the ReDeads wear. And if you look at the official artwork you can only see the teeth of the ReDead through the mouth hole in the mask. This is because the lips often recede on mummified bodies and I imagine...
Smash isn't canon so I wouldnt take what it says seriously. Redeads are clearly reanimated human corpses. Their existence actually seems to not be connected to Ganondorf and are unlikely his creations seeing as they existed before he came to power and in places he had not visited.
I don't know...