Board Thread:Theories and Speculation/@comment-24824859-20151203011901/@comment-945885-20151204013943

Thekillman wrote: Elveonora wrote: The Otsutsuki were not humans According to the definition of a species, they're humans. No, the Otsutsuki are an alien species of sapient humanoids. Thus far there is no evidence that they are related to the human species, beyond being able to mate with them (which in the realm of fantasy and science fiction is essentially meaningless).

In the Boruto novelization, Kinshiki and Momoshiki are described as ogres (鬼, oni) rather than humans. You could interpret that as simple metaphor, referring to their horns and such, but you could also take that to mean that they clearly aren't human.