How do ordinary average girls get a good-looking guy?

By being girls, that's how.  That's the same way the fat ugly girls get guys, in fact.

There's a simple rule when it comes to 'getting' people, and it goes like this:  Girls have what guys want, not the other way around.  There are very few guys who can literally get any girl they want, and those guys are all filthy rich and usually good looking.  There are billions of girls who can get any guy they want, because that's how it works.  Even the gorgeous popular guys have to compete for a girl's attention, and even the ugly girls can get laid whenever they want just by saying yes.  

Those guys don't find the girls ordinary or average. They don't pride themselves of being good  looking too. 

sex.   gifts.   stunning personality

The criteria here is too subjective.