Kpop is cool and all but not a great way to see the differences in people. Kpop idols are routinely made to look like other popular idols to appeal to a larger fan base. This happens in other cultures as well, US actresses for example!
I would suggest you stick with Dramas to get a better mix of people. And mix it up by country. Add some Thai, Japanese and Chinese dramas to your watch list. At some point you will see the vast differences in just one nation, China is quite diverse in looks, Thailand as well. And it can't hurt to experience music and dramas from other parts of Asia like Vietnam, Malaysia, Singapore, etc.
And don't just limit yourself to Asia, really look at humanity. You would be surprised how often you can see the similarities between cultures. American Eskimos having Chinese traits. And I don't mean eyes, facial architecture varies worldwide.
In America people think anyone Hispanic/Latin is Mexican (which is SOOOOO false). But Central and South Americans are just as diverse. The larger the mix of people from a continent you are exposed to, the easier it is to get a sense of where they may be from.
All of humanity migrated from someplace, and we still do today.