Good quiz, thank you. How about "Dodo Bird" for unintelligent person? Could also add "free as a bird," "bird's-eye view," "for the birds," and "kill two birds with one stone."
The "unintelligent person" clue could be improved. In many areas, it's used more to indicate ADD-type personalities, or ditzy/scatterbrained characteristics, rather than simply a lack of intelligence.