Why are alot of jamaicans light skinned?

I ask because, there is a boy in my school from jamaica and he has blonde hair, hazel eyes, and skin about the color zac efron. But he has a shaved head and you can tell that he has coarse hair. Also my old crush is light skinned and he is from jamaica, but he is the color of beyonce. His mom is the color of zac efron with light brown hair, his mom can p for somebody who is mixed with white. But his mom is all jamaican. There are more kids in my school that are really light colored and are jamaican, and their all black. Why are so many jamaicans light skinned?