NPCs can vary in 4e. Full on statblocks are most often idiosyncratic monster math and full monster role ones, but there are plenty of monsters designed on class concepts and NPCs described as classed individuals.I don't think Nentir Vale is a good example because it's a pretty generic setting that could work with any fantasy game. The only things it really takes into account is the existence of Dragonborn and Tieflings along with the other PHB races at the time. It might take ritual use into account, but it's not like it has NPC's that are specifically members of a character class (since NPC's in 4e are designed completely differently than PC's).
In H1 Keep on the Shadowfell on page 9 for instance: "Lord Padraig: From time to time, the town’s lord (level 3 human warlord) visits Wrafton’s. All those present doff their hats and call him Lord, after which he retreats to a corner table and sips beer."