No you're not dumb, you are correct. Remember how the "zombies" (they're actually not quite zombies in this movie, less so in the book) were standing under the building/archway thing with the mutated attack dogs (that were collared and chained btw, just showing that they are decently intelligent), waiting for the sun to set so that they could attack him while he was hanging there?

They set it up for him because earlier in the movie, he set a trap for them.

I am pretty sure the film referred to them as "Vampires".

I mean, I dont remember much from the film but couldnt they infect you? And they also couldnt go out in the sun or else they would burn? sounds pretty Vampire to me.

They are definitely closer to vampires than zombies, but I don't think they ever explicitly say if the creatures are one or the other in the movie or the book.

I'm not sure if the creatures can spread the virus themselves or not. In the movie, they make it clear that the infection first spread like a normal disease's pandemic. I know Will Smith's character was never infected, but he was immune anyway.

In the book, they're referred to as "dark seekers", seeing as they can't survive in the light. Also, they aren't zombies or vampires, as they are not undead. They're still living humans, infected with a virus that messed with their genetic code. For those who don't know, the virus was caused from the doctor's cure for cancer.

I forgot, how did his Dog get infected?

Oh wait, I remember how it works now. Will Smith's character says in one of his audio log - things towards the beginning that humans were getting infected by the virus that had become airborne. Then he said that animals were unable to contract it from the air, only by direct contact. So that's why the dog was infected once it was bitten by the infected dogs.

So I guess you were right that it could be spread by the creatures themselves, but since a person would potentially be infected once they took a breath in that city, they would turn (or die) before ever being bitten.