Anyone ever wonder why a guy or girl would wanna be with you?

Ok, so self admittedly I don't consider myself the greatest looking guy and I will admit that. However, recently this very attractive girl that has beautiful blonde hair, blue eyes, a great body and an even better personality has been flirting with me, a lot! I'd consider myself to have a very good personality but that has never seemed to attract girls for me, yet this girl flirts with me like no other girl has before and I just feel like looks wise she is way out of my league. So you ever feel like you aren't good enough for someone that wants to be with you?