I knew this word, but never used it like they do in England. I guess daft is uncommon here in the USA, however, the world is full of daft people. Collins dictionary defines daft as: “If you describe a person or their behaviour as daft, you think that they are stupid, impractical, or rather strange. [British, informal]”
Silliness personified as
Dumb as a box of rocks
Fruity as a nut-cake
Name calling and labels can be very painful. I tried to give it a lighter touch.