I like to put it another way. If History is a computer, then it spit out an answer 246 years ago—The United States. Of course, the computer is still running and working on the next answer but now it's based on the previous answer. In other words, all those ancient cultures interacted for centuries in bloody and commercial ways, exchanging cultural ideas such as noodles from China becoming pasta in Italy becoming Dominoes Pizza in America (and lots of way better pizza). By doing away with the kings and emperors and sultans and reveling in Freedom of Expression and welcoming the intrepid, bold immigrants and fostering free market competition we created a crucible for volcanic creativity that literally synthesizes every culture into new things, including a heavy dose of African. This is so powerful an influence that it created English Language jazz, blues and rock which then infused England to produce the Beatles, Stones, etc. just as Boy Bands from the US spawned KPOP as you mention.

So it's not strange that US culture is pervasive because it's really World Culture that folks can relate to because they see a little of themselves in it. That's much harder for more monolithic ancient cultures to do because we often don't see ourselves reflected the same way because it's more specific and less general.

In conclusion, everything is evolutionary and just like with genes, memes (ideas) are also subject to survival of the fittest and the ones with the most diversity are generally more fit, just like with genes.