humanity isn't the only intelligent race the earth will ever produce, our time as the top species of the planet is limited, and there is a species in the past which can project themselves through time to take control of earlier and later beings to have a complete history of the world and therefore the most thorough possible scientific knowledge. Lovecraft lived after Darwin; the first two of those points should not have come as a shock, and the third… well, so what? Disturbing, but not insanity-producing. But then Lovecraft was a racist so extreme that even in a time when public blatant racism was common other racists found him disturbing (many of the monsters in his stories are exaggerated black/asian/semitic stereotypes, although not in this particular story), and so the idea of anything other than a white male human being as the supreme ruler of the planet would really drive him nuts.
