Responses
http://www.mangago.zone/read-manga/candidate_for_goddess/mf/v05/c020/32/
from volume 5 page 32-34, i think the "experiment" is Rei(Zero). so technically, Zero isn't a "human" but a created being ... probably.
There's so many holes in this manga. One of them is in volume 5 page 83, it seems to be saying that Zero is not human. If Zero is not human, then what is he?