Most of the "monsters" are actually immigrants
The reason why the kids find them strange is because of their accents and they behave strangely due to coming from different cultures. This series takes places in the same universe as Courage the Cowardly Dog
There will be a tv series adaptation of the books in the near future.
C'mon, we got one for Nate the Great, and Captain Underpants, and we're getting one for Junie B. Jones soon. If there's any book series that deserves a TV show, why not this one?