No no no your observation is right on point, the webtoon is korean so they use neutral(idk how to name it) pronouns like they/them to address children or just say "baby". But the only confirmation on the gender we can get is in the piss episode. LMAO
I just realized that the translation always refers to Mori as "child" and "they". I've always thought Mori as a boy, but could it be a girl?