Are some fast spiders aggressive toward humans?
Cannot identify the species from your description and the behaviour cannot be worked out from what you say. A spider is unlikely to attack a human. They just see us as big and therefore too big to attack. A spider may defend itself but it is not going to make an unprovoked attack on a human.
The thought of that is terrifying
Yes some spiders are aggressive and will attack if threatened. Others will only attack if they have no other choice.