Yes, leave everything alone. The valve you describe is used only to divert incoming city water to fill the tank. Once the tank is full, that valve is returned to the "city water" position to either use the pump and draw from the tank, or to use city water directly from a spigot.
As mentioned, simply hook up your hose connection, leave the pump OFF, and you will have water flow under pressure from the city service.
Larry, Eileen, and Finley
2004 Alpine 36FDDS
Third motor home, first Alpine, no need for another.