not a dumb question at all....

how wide should your handlebars be? that depends. i recently went to wider bars. wider bars at first felt odd, but gave me more control. now they are super comfortable and i prefer wider bars. so comfort is a factor. some like shorter bars, for tight spots or, again, comfort. really, i don't think there is a right or wrong answer. yes, you can get too wide, and yes, you can get too narrow, but i'm talking extremes.

if the bars are slightly wider than shoulder width, that is ok, as long as your arms aren't stretched out like crazy.

ultimately only you can determine if your bars are too wide or too narrow.

if your bar is too wide, and you want it shorter, you can cut it with a hacksaw.