Before our heroes/victims happen on the cave system crawling with human-eating anthropoids, how did these things sustain themselves? They need to eat whether or not 
it's open season on college kids or free-range extreme sportspeople, or whoever comes knocking.

Presumably the creatures also take a while to raise, during which time they don't hunt for themselves. Some kind of parenting is necessary for the species to 
continue.

The site is remote (or they'd have encountered humans in great numbers already, and would have come off the worse). Is there enough food for hundreds of hungry 
carnivores in what's likely to be a fairly enclosed territory? 

They can't feed solely on each other, and even if they did wouldn't it be lossy and therefore unsustainable?

Can they enter a dormant stage and, if so, wouldn't they be vulnerable to other predators and scavengers?

Some of these problems could be solved by switching to a more populated environment. What about tunnels under landfill, or grazing the sewers for those lovely, 
high-carb fatbergs?