I’d have picked the Manhattan Project, ARPANET/Wikipedia, and aerospace development in the wake of the Wright brothers.
Many of the ones you’ve listed would likely have happened whether or not the USA-qua-USA existed. The Manhattan project and the current internet and the rush to build airplanes (first as weapons of war, of course) would probably not have happened the way they did without the USA.
You’re probably wrong about this but will never admit it.
This is because you have an ideological commitment and are backing into the answer that is orthodox to this commitment, rather than any real rationale or spirit of inquiry.
Many of the ones you’ve listed would likely have happened whether or not the USA-qua-USA existed. The Manhattan project and the current internet and the rush to build airplanes (first as weapons of war, of course) would probably not have happened the way they did without the USA.