children's long hair, small child
髫 centers on the long, unbound hair of a small child, and by extension the child itself. The two given meanings are closely linked: the distinctive hairstyle represents the young child.
髫 combines 髟 (hair) with 召, which likely provides the sound. The character specifically refers to the long hanging hair of children in ancient China.
The top 髟 is long flowing hair, and the bottom 召 looks like a small child being called. Picture a little child with long, unbound hair running when called.
For チョウ, imagine a child with long hair named Chou: Chou -> チョウ, and the child's distinctive hairstyle makes them easy to recognize.