EX: This is more than a decade out of date, but it's a useful reference. https://en.wikipedia.org/wiki/Superpower#/media/File:1_AD_to...
Don't let the prominence of discussions of China's "rise" fool you though, it is most certainly not a superpower. It certainly has the capacity to be one some day, but its power projection capability is fairly restricted to its immediate vicinity in East Asia still.
I say thank goodness military might is not the only measure of power or we'd be in a sad state of affairs when you come to think of it. That's not to undersell the force projection of military might, and does not deny that the US (and Russia to a lesser extent) derive enjoy an outsized place on the world stage owing to military might.
Put it another way. You may be right but I do not want you to be right. I don't want to live in that world.
If you discount China as a superpower, then you discount a country that could single-handedly throw the entire world into a state of political, economic, and military chaos overnight.
Defining power as military-only is as naîve as defining it as male-only or violence-only or sword-only.
You are right. One should take care defining a word so narrowly that it can only apply to one thing. If "superpower" by definition means "characteristics only the USA has" then why not just call it "USA?"
What is the quantitative metric of this?
But if you want to wage war on China be prepared to go back to the 50s. China and its immediate neighbours make everything. And have done for decades. No country has the standing manufacturing capability (facilities, machinery or trained/robotic workforce) to replace what China does for them. Some other Asian countries manufacturer electronics and India and Pakistan do textiles like nobody's business.
This is where that influence from earlier came in. They've traded cash for foreign government bonds to ensure great tariffs and to stop protectionist policies. They pegged their currency to ensure their exports undercut everybody else.
Automobiles are pretty much the last serious manufacturing done in market countries... And where do you think many of those source their parts and steel from?
So yeah, you piss off China and they have the physical wherewithal to embargo almost all material imports. Your economy dies overnight.
You take back a bridge and a nuclear power plant. Big whoop. What's your next move?