whats with humans and nobles?
Historically speaking, the longer a human society exists, the larger, more bloated, and more privileged it's ruling class will become. MWDF humans have lot in common with a typical medieval Italian city-state. At the top you have the King/Queen who may claim to be divine, followed by rich estate-holders like Counts, followed by village Mayors with whom the higher nobles consult with to inform the masses of the state's demands, and finally you have the general bureaucracy that actually does the paperwork in telling the peasantry what exactly needs to be done.
For the purposes of playing, just think of the potentially infinite nobles as a way to get special treatment for your favorite workers without pissing off the other "real" nobles, with the added bonus of never missing out on a good trade deal just because the broker decided to take a nap immediately after he went off break.