What you neglect to mention is that American economic hegemony was built on decades of ruthless protectionism, exploitation of vulnerable nations (including the UK) and lethally brutish enforcement of its neoliberal fundamentalist theology on other nations – cf Ha-Joon Chang and Naomi Klein. China is following the US’s example and is likely to become the global hegemon, that none can resist, within a generation.
The US’s transition to a services-dominated economy and perpetually mounting national debt came after the abandonment of Bretton Woods and the gold standard made the US the “consumer of last resort” and made the dollar the global reserve currency. These developments had nothing to do with benefiting the whole world and everything to do with instituting American world domination – economically, militarily, diplomatically, politically, culturally – the folly and futility of which becomes more apparent with every passing day.
You are right that “making America great again” is a quixotic mission. You are also right that there can be no return to a golden age. However, simply hoping for a return to the status quo ante is no solution either. What is required is a global equilibration of economic activity, wage rates and skills and freedom of movement of goods, people, services and capital. Nationalism in all its forms is a bad idea. Everything now requires global planning rather than “globalisation” which has been a cover for asocial, amoral seedy barbarism.