2016 Cedar Creek Cottage 40cck plumbing
Not familiar with the exterior layout of your unit, but most have just a few options.
If your unit has a compartment with all the water connections and valves. Where you connect to your campground water source there may be a valve directly above the connection, make sure it is turned to city, the gravity position will fill your fresh water tank only, as you have described. Your water heater is a 20 gallon residential one it will take a little bit to fill it once you get water to the faucets. Do not turn it on until you have a steady stream of water at each hot water faucet.
If you have only separate exterior connections make sure you connect to the city water connection, again connecting to the fresh or gravity connect will only fill the fresh water tank.
There is one other possibility, but since you are not getting any water at all from any faucet, it is not likely to be the issue. The check valve in the fresh water line could be stuck open allowing water to flow to the fresh water tank, but usually when this happens you also get water from your faucets.
Let us know how you make out.
Disregard my post you all were posting as I was writing, glad everything is ok. Happy Camping