It drew from classic heavy metal, NWOBHM, hardcore punk, and its own unique energy to create music that was more aggressive than any at that time.
Thrash focused more on rhythm than older metal, abrasive picking, and speed, while retaining intricate riffing, complex compositions, and moments of distinct melody.
It paved the way for death metal, grindcore, and black metal.
Nothing projects energy and aggression like thrash.