I don't get what you're trying to say, do you mean that not respawning humans would make the game like a regular zombie survival and how everyone is going to die if one person dies?
I honestly don't get why would we need to respawn humans, that would make the game pointless for the zombie team since humans could just act like an alive wall to defend the VIP.
I'm saying that humans will still die with the downside that if a certain person dies (the VIP) everyone dies.
To fix the OP humans, how about 2/3 of the players zombies like memo said?
How about this, nobody will be redeemed until the zombie team reaches 2/3 of the players in the server. Once this happens, the remaining humans will be redeemed whenever they are killed (NOTE: If they are killed by anything other than zombies, they will not be redeemed) That way, humans can't make a giant wall over the VIP and the humans won't be OP.