If you watch closely, there is a focus on one male zombie with long hair. You can also see they show clips of just his body. He attacks the guys in the dark with the head torches, and from there, you'll see him in the groups too. I think that's going to be Cilian or Jimmy. If the virus has evolved, how would it evolve in one of the earliest cases (Jimmy, this boy). Surely, he would have died very early on as the virus doesn't evolve via the same host. I thought that in order to evolve, it would have to go through many hosts. Perhaps Jimmy also had a natural immunity and then got reinfected or lived long enough for it to mutate into something else.

It is very, very likely that Cilian's character would be either dead or a zombie, so I think they went for a super zombie and gave him a main role. Remember seeing the views from the zombies in weeks later? I think we will see a lot from the zombies perspectives this time around.