I mean, even if Trayvon struck first, i can kinda sympathize with him. a strange guy was following him in the night it was preemptive self defense
This. But of course only the winner can claim self defense
Because there is no such thing as pre-emptive self-defense. Trayvon was the aggressor and smashed Zimmerman's head into the pavement because he wanted to seem "hard" and not back down after talking to his girlfriend. That took away any claim he had as the victim in this case.
Zimmerman was the aggressor and followed a kid with a gun.
Following someone isn't an act of aggression. Smashing their head into the sidewalk is. ---