The Enormous Crocodile grows more and more hungry as the story goes on and his attempts to eat the children are foiled. While the story portrays it as him being greedy, in real life, crocodiles are ambush predators, meaning they wait for their prey, rather than cross miles of jungle as it takes up too much energy.
The Enormous Crocodile and The-Not-So-Big Crocodile both comment on the taste of children. The only way they'd know this is if they have either eaten children before or know someone who has.
