International air traffic is growing, but so are regional airlines. Cultural evidence is equally double-sided. The number of published languages has increased, not decreased. So there is no point in detailed argument, about trade volumes, capital flows, and information flow. There is a simple answer to this confusion of logic.
Nation states are one of many possible forms of state.
The mere fact that there is a world of nation states indicates some form of global order of nation states. What they do, trade or no trade, flows or no flows, is irrelevant - to that issue at least. What is already global can not logically be globalised. Therefore there is no globalisation. The world functions as if a nationalist world government had seized power in the last century, led by Mazzini and Garibaldi and friends.