>The US suffered less casualties than all the other major powers (USSR, China, Germany, Poland, Japan, France, Italy, UK) in WW2 and their infrastructure was not destroyed. So kill/death ratio and net destruction are quite indicative of the outcome.

You're moving the goalposts now. Your earlier comment claimed the method for becoming a superpower was to "participate in the most wars and murder the most people." The number of casualties or infrastructure damage relative to the rest of the world shouldn't matter, as that implies a degree of complexity in the nature of superpowers that your prior rationale doesn't allow for.

>Which country would you guess has committed the most large scale invasions and longest lasting wars since world war 2?

You obviously want me to say the US, and you're hedging your bets with the weasel terms "large scale" and "longest lasting" and I really don't care enough about this to go look it up, so fine... the US. But since the US was already a superpower after World War 2, that's not really germane to the US's rise to superpower status.

>Did the Mongols not achieve their super power status because of how successful they were at mass murder?

Maybe, but the point is that the US didn't achieve superpower status through success at mass murder, and that they're not like the Mongols.