In some ancient civilizations the Wolf was a symbol of the underworld. In Egypt, the guardian of the dead was Anubis who was a wolf-headed god. The jackal portrayed as black was the symbol of both death and regeneration.
William is also the one who hid inside the suits and kidnapped and killed children, leading to the assumption that William Afton is The Purple Guy of FNaF 2 and 3 (he is killed at the end of the book when Charlie sets off the spring locks in his suit).
The purple moss guy, I'm looking at it now and it's a small piece of moss but the whole thing is purple and in the middle it has a brown/dark purple look to it and they are shaped like leaves but there not leaves. Hard to explain without the picture.