Babies first sounds are usually a consonant followed by a vowel. So ma, pa, ga, gu, ba. A few months later they start duplicating the sounds while testing out their speaking abilities so you get mama, papa, gaga, googoo, baba. Which are common first words for lots of baby things. Like baba for my sister was her bottle. Every baby might not say every variation while they’re learning and they will obviously have favorite words but generally that’s why we consider baby speech like that. Maybe english just happens to choose the “g” for the leading consonant because we have a lot of hard g words in english and that’s what babies pick up on first.