A generic noun (ism al-jins) denotes a class or kind. Thus “asad” ordinarily denotes the kind lion rather than naming one specific individual. A salient resemblance can make that class-name available for metaphorical transfer.
A literal generic noun already expresses a kind by its conventional meaning. A generic noun by interpretation results when a famous proper name is treated as denoting a class of people sharing its celebrated trait. This does not happen automatically whenever a personal name is mentioned.
The distinction explains why the metaphorical use of “lion” is straightforward, while a famous name requires a special semantic interpretation.