He's still a greenhorn, so we can't entrust him with important work.
What could such a fledgling possibly understand?
A humble or formal term for a young or inexperienced person, often used self-referentially.
Compound of 乳 (milk) + 臭 (smell) + 児 (child), literally 'milk-smelling child'. The exact historical derivation is uncertain, but the term has been used figuratively since at least the Edo period.