just like the halfling section in riverhaven is halfling only, and some homes near the reaver caves are dwarf only -- rossmans has some human only homes. If you are dead-set on getting a home in rossmans, just role up a human to claim the home, your elf <on the same account> will still be able to access it and utilize it.
<<Because it's a gigantic can of worms. Eldritch, necrotic, squamous worms, writhing in a vile stew of coagulating ichor, crushed from the living gullets of a thousand infant puppies, ululating in wordless terror. - Lorz>>