This emoji was created to focus on the concept of a 'child' itself, without gender stereotypes. That's why it's used with a more inclusive meaning than the 👧 (girl) or 👦 (boy) emojis.

It's one of the emojis that reflects the social trend of respecting diversity. Since it doesn't specify a gender, it's useful for representing a protagonist in a story or an anonymous child. It also represents the feelings of people who want to keep their childlike innocence regardless of age, like a 'kidult' (kid + adult).