WHY. . . (so very annoying -.-)

so im 16 yrs and a sophomore in hs all my life girls(my age slightly younger and older) never really were interested in me i was always standing in the shadow of one of my (maybe) better looking friend. only the girls that were my age (not very attractive) took an interest in me

all my life some younger girls (2-4years younger) started to like my (flirting with me whenever possible) but back then i never really though anything about it i just dismissed it

but recently i have been just chilling in parks and librarys and only younger girls (lots) actually make an effort to talk to my

i kinda find it a little embarrassing and very annoying when lots of young girls start trying to flirt with you . . . my friends that are my age are looking at me weird
them-yo bro why you going after little sally
me- i aint trying to get that

so why are the young girls are going after me??
is this normal??
why do i feel embarrassed?? age is just a number right?