'All possible worlds' does not mean 'All imaginable worlds'. 'All possible people' does not mean 'All imaginable people'. Past a certain threshold of specificity, one goes from {general types of people who exist almost everywhere, universally speaking} to {specific types of people who only exist in the imaginations of people like you who exist almost everwhere, universally speaking}.

Congratulations, you have discovered that most philosophy isn't worth the paper it's written on.