I dont think that the
Little Ones are kid zombies.
The Kane Medical Institute which was Ink's workshop, where some think he was tattooing the little ones, is located inside
the hospital.
Kalani and
Riley mentioned seeing bloody drag marks all over the area.
Do you suppose that Ink has some way to figure out which person changes into the different kinds of zombies ie.
runners,
jumpers, behemoths, and
smart ones? Then he has those people captured and brought to him so he can change them.
Or better yet mixes different kinds of drugs or pathogens with zombie blood (they are in a hospital) to create different zombies. Steroids for behemoths, human growth hormone for fast ones, that kind of thing.