Literary analysis: This verse is paired with the next two as parallel images. Each set consists of statements indicating contradictions in the normal behavior of animals, and finish with some unusual behavior of a child.
This verse underlines the remarkable peace of the future kingdom by showing the contrast of predator and prey remaining side by side in peace and safety. Even the order of nature will be improved an brought to peace. If the natural predator might have no desire to kill its prey, so much more will the human predators also be pacified. Notice that in each case, it is the mature predator and the young prey. The peace will be great enough that eve the defenseless will have no worry.
This remarkably passive state is then highlighted by the indication that a child could lead them. Not only have the young and defenseless animals nothing to fear, but the predators shall be sufficiently peaceful that a young child might safely lead them.