This is what the characters from Equestria Girls would be named if they were given actual human names.
 
I always saw that Twilight, Luna, and Rarity would seem like names that would actually exist. I would’ve given Twilight and Spike the surname, Sparks, but that would’ve been obvious. And yes, I’m in favor of human spike.
 
In regards to some of the last names, I always saw human Rarity as being Franco-American, based on her use of French words and phrases, and that she has a face of someone that would be of either French or Latin descent, so I gave her a French last name. And I always saw human Fluttershy and Rainbow Dash as Greek America, based on that Cloudsdale, their home town, is influenced by Greek architecture and culture. Not to mention that they somewhat have the same facial features of someone of Slavic descent.
 
*Update; here is a revised version:  
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