A mage in Momotto, the most technologically advanced country in Ennen, made a wind-up toy. He then reasoned that since kids love wind-up toys, they'd love it even more if the toys could move on their own! Unfortunately, when casting that particular bit of magic on them, he screwed up and also gave them some degree of instinct and the ability to self-replicate.
Heck of a spell.
So now these guys, nicknamed winders by the locals, wander the jungles. Being made of metal, they don't have a lot of predators, but they don't really eat, either, so there is that.
See? Not everything in Ennen is incredibly lethal. Just mostly everything.