Being an initial zombie is boring because you’re either (a) farming morons and AFKs to redeem because it’s easy but also because it won’t affect your victory chances much, or (b) you’re “z-maining” (intentionally or because you know you’re not redeeming) but early on, you’d mostly only kill morons and AFKs that can’t move the round so you just sit in spawn chatting and watching YouTube videos on your other screen for a couple rounds.
The first zombie players aren’t doing shit unless there’s fun and purpose to be found in actually playing. This means you should be able to score kills and get a game going even if the humans are all top tier players. This in turn means giving those first zombies major, major assistance. It could be a “patient zero” status with insane stat buffs that carries over deaths but tapers off as the infection grows. I’m not sure how this specific example would interact with barricading and the point economy but there has to be a way.