It all depends where you are on the scale between technical and casual, formal written English and slightly childlike English, etc.
"Creepy-crawlies" is not a formal word. I'm not entirely sure I will find it in the dictionary. (It's there. And it's described as "informal.")
"Creepy-crawlies" is a slightly childish word. It applies to any small thing that creeps or crawls. It means something the speaker doesn't like. The speaker thinks they are repugnant (formal word) or icky (informal word). The speaker is intentionally not being precise.
Creepy-crawlies! Ick! I don't even want to know what they are! I'm going to look away! I certainly am not going to to count the legs and tell you whether it is an insect or spider!
Creepy-crawlies would include true insects, but also spiders, scorpions, earthworms, centipedes, millipedes, slugs, and quite possibly small frogs, small snakes, lizards, newts, etc.
And there are insects that are not "creepy-crawlies." Butterflies are insects, but they are beautiful and people like them, so they are not "creepy-crawlies."
Ben Hoare is saying that people like watching cute, small mammals (with fur) and birds (with feathers). Many people are repelled by all the cold-blooded animals. On Facebook, people don't post adorable pictures of cute scorpions doing funny things.