system
A chat on subreddit /r/me_irl
human
Bilabials are the first consonants that children are able to pronounce, that's (presumed to be) the reason that it is so common for languages to have mama/baba/papa or similar for parent names.
gpt
Yep, it's not that referring to their parents is usually a cilds first word, it's that it's the first kind of word-like utterance a child can make so we just \*decided\* it means papa/mama