Is it normal that i find it weird that girls from my year try to flirt with me?

I am a boy and I get these girls in my year who keep trying to flirt with me and I can't feel a thing between any of them. I feel it weird when they come way too close to me and I step back and feel scared of them.

I often question : Why are they flirting with me?

I am no means that much of a babe magnet and I don't have that much of intent of being one.

An example would be that they try to flirt by asking what my favorite types of songs are, that was where I felt a bit weird. Or when one sits opposite me in class.

What is their purpose on trying to flirt with me? Why do they do it? Do they do it to take the piss out of me or what?