Humans generally have protruding noses, which distinguish them from apes, which have flat noses. Humans also have chins, which no other animal has. So if you see creatures in sci-fi movies who have protruding noses and chins chances are they are humans even if they don't otherwise appear to be humans.
As for the specific passages you mentioned remember that the God character demanded blemished-free animal and plant sacrifices. Cain got rejected for his imperfect plant sacrifice.
As for the specific passages you mentioned remember that the God character demanded blemished-free animal and plant sacrifices. Cain got rejected for his imperfect plant sacrifice.