That Internet again, conflates all the sources and dictionaries, gives me almost endless lists. I don’t remember which word got me started, but it triggered the following:

Throttlebottom: innoculously inept and futile in public office.

Ninnyhammer: in American English, a fool or simpleton, ninny.

Snollygoster: US dialect: a shrewd, unprincipled person.

The differences between otiose and nugatory: nugatory suggests triviality or insignificance. Otiose suggests that something serves no purpose and is either an encumbrance or a superfluidity.

Bumfuzzled: in a state of bewilderment: confused or perplexed.

Flibbertigibbet: a silly flighty person.

Poltroon: noun: a spiritless coward: craven. Example: “I am a poltroon on certain points; I feel it. There is a base alloy of moral cowardice in my composition.” – Charlotte Bronte, Shirley, 1849.

Slobberdotcher: an idle person.

Slobberlatcher: archaic, a slovenly or worthless person, one who never works hard.

Pogonotrophy: the cultivated or growing of a beard.

Purile: juvenile, childish, silly.

Flapdoodle: noun, slang. Foolish talk; nonsense.

Codswallop: British slang. Foolish or meaningless talk; nonsense; rubbish.

And the list goes on…