I didn't quite get the sense that Ai Ling understood or that it was shown that regular human beings were just as likely to be the most dangerous thing she encountered.

In the scene where Chen Yong pulls her out of the water, I put it down to her being simply relieved that there's a human being, i.e. someone like her, nearby, as opposed to scary mysterious creatures. As for the rest of the journeys, yes, it is a bit convenient that she doesn't run into, say, a swarm of bandits while she's all on her own. I suppose it's because Pon wants to concentrate more on the supernatural beings as dangerous angle?

Zhong Ye is introduced a little late in the story, but OTOH, no one could have told Ai Ling about him at the beginning.