What's the non-binary equivalent of the term "manchild"

Piss baby.

Large adult child

"absolute toddler"

"deeply unserious"

Dirt Owl

Personbaby

Kiddult

Considering my last several years worth of experience, I think the term is “adult”. Sadly.

themchild

Large adult child

Big baby?

Large adult thembo

Puerile pal?

Adult Human Child

I don't subscribe to the binary of "child <=> adult". I'm transjuvenile.

Arrestheyd Themvelopment.

Fetus

for a certain subset, demiman child

The term is Felix.

A neotenoid, or maybe neotenist