Hello IanMegill and Kafetzou,
sorry for being late, here is my explanation.
Kafetzou we never say "insani (in fact this is written "insanî", and it is adjective) bilmeyen insansın" instead we say "insanlığı (this is a noun) bilmeyen insansın". also this "insanî" is never used in such a context. So there are two "insanı" here.