That's the unfortunate truth to the series, but alternatively its greatest asset. I'd love Pokemon so much more officially if they spent more time making the creatures interesting.
ON THE OTHER HAND...
Since they're all bland and generic because each Pokemon is part of a species and not an individual, it allows fans (like myself :P) to come up with their own interesting versions of the creatures (even within the same species). It's probably one of the most open franchises for fans to use their imaginations.
To answer the question though, I don't think I've ever cared about the humans, save for the Team Rocket Trio. As I always say, if I wanna play with kids in hats, I'll play EarthBound. Otherwise, I'm in it for the monsters.