"Do guys like curvy girls or skinny girls? Do girls only like muscular guys? Do men only like really thin girls? Do women find chubby men attractive?"
Everyone has different preferences to what they like in the opposite or same sex. If you meet a consecutive number of women who say they love guys with six packs and a muscular physique, that doesn't mean all women find only muscular men attractive. Even those who say they only like muscular men wouldn't turn down a lovely man just because he doesn't have a six pack (those who do are incredibly shallow). I know many women who find skinny guys much more attractive than muscular men.
If you find that a guy has only ever dated really short girls, it doesn't mean he would turn down someone for being tall or that he's only attracted to really short girls. If he was a decent person, he would base most of his attraction on your personality, not your physique. If you tried to work out someone's type by who they date, then you'd be mistaken in thinking I only go for muscular, martial artists when in reality, it was pure coincidence! I've had people tell me that I only date white guys but that's because I don't know many black/asian guys - I've never ruled them out!
What I'm trying to say is that everyone has preferences but it doesn't mean they're limited to just one or they're really strict about them. A vast majority of people have a variety of preferences or they have no preference at all. People don't care about ethnicity, religion, skin colour, height, size etc, as long as that person treats them well, they find them attractive and offers what they're looking for in a relationship.
Beauty is in the eye of the beholder
You shouldn't be concerned when you see people usually going for one kind of person. Don't quit in trying to date someone because you think you're not their "type". If you don't know them well, how would you know what they prefer anyway? If you feel like you don't fit in with society's expectations of beauty, I can guarantee that there are people out there who would find you attractive and would want to date you, you just have to find them and you shouldn't beat yourself up about it!
You are beautiful ☺