There is no free will in fictional stories none of the characters have a mind of their own, they all act in ways Oda, the creator of One Piece, wants them to
So if Usopp is weak and can't defeat a cat it's because Oda wants Usopp to be weak
If Luffy calls out Usopp, it means Oda is calling out Usopp for being weak
But once again Usopp isn't real, his will is determined by Oda who criticizes him for being exactly the way he wrote him to be