Think of it this way:
Let's ask ourselves the question: Why do we like things? The answer, of course, is that the things that we like have certain "likeable" qualities that MAKE US like them, so in other words, I like music because it (has qualities that) MAKE(s) ME like it...
So, let's say you like classic films = team gustan las películas clásicas = classic films MAKE YOU like them
She likes fast cars = le gustan los autos rápidos = fast cars MAKE HER like them
But if she likes you, it means YOU have certainly qualities that MAKE HER like you = you make her like you = le gustas (tú)
The same if she likes me = le gusto yo
The same if she likes us = le gustamos (nosotros)
Based on the above logic and examples, it should make sense to you now :) It's true that most examples will be either "gusta" or "gustan", but not whenever someone likes you, me, us, or even more of you in peninsular Spanish (eg. she likes "you guys" = le gustais vosotros)
Hope this helped! :)