An animal did evolve as a specialist predator on humans, as remains in caves in Africa have shown. Its name is Dinofelis, and its signature is a pair of puncture holes left in the skull. It has survived in folklore and even in our most basic instincts: every child knows that there is a monster under the bed, and the only way to stay safe is to keep very, very quiet.
The first two answers are not correct, in my opinion. The first says that mosquitoes are that animal, the second says that humans are that animal. Nah. It’s the skull-piercer up there. Be very, very still, child.
The link references studies that showed little children are instinctively good at hiding from large predators.