Saying Americans believe they have some heaven sent mandate to save the world sounds like an isolationist position popular with whichever party is not currently holding the presidency. After WW II the Japanese saved Japan and the Germans saved Germany. People should understand the best one can hope to achieve is establishing an environment conducive to governments lasting more than one generation.
I think we have an obligation to base our foreign relations on the intangibles which define the best aspects of our character, and move on to real politick reluctantly. Otherwise prosecuting national interests means making a deal for access to economic resources with the ruling elite of the ascendant tribe for a generation, when the next revolution comes along.
The overwhelming pulverization of enemies in World War Two did give the US the opportunity to order the non communist world in a shape that it desired more than any nation before. Fixing security and economic arrangements so we could run the show is not Wilsonian globospeak but real politic disguised as moral crusading. It certainly was good for the US. If it helped others fine but that is incidental to me. We exist to help ourselves pure and simple and anything else is dangerous and delusional. (Although we have had plenty of those things in the history of our foreign policy.)