a monkey wearing a crown; someone unsuited to their position
A classical idiomatic expression meaning that someone merely looks the part but is completely unsuited for the role. Rare in modern conversation; mostly encountered in literary or historical contexts.
He became the company president, but he's like a monkey wearing a crown.
From the classical Chinese expression 沐猴而冠 in 『史記』, literally a macaque wearing a cap, used of an uncivilized or unworthy person occupying a distinguished position.