Yeah, like Daering said. Get Kael to 6*. He'll be your campaign farmer and he'll be pretty much in all your teams early on. 

As for your current champions: Marksman can be good for CB. Always keep a copy of rares and epics in case they get used for fusion in the future. 

I also don't see a lot of wow champions there, but definitely Shaman, Fang Cleric, Marksman, Doomscreech, Heiress, Warpriest should have their uses early on, even if they aren't worth putting skill books in. As good as Kael is, he can't exactly do everything on his own. 

Keep in mind the Faction Wars part of the game, where you assemble a team per faction. Most of Faction Wars is very, very hard and for expert top level players, but the first few levels are doable quite early on, and can get you some nice rewards (without costing any energy!). For that, you'll eventually need a lot of champions in which you don't invest heavily, but you do want to level them up a bit and give them some sub-par gear that isn't good enough for your main champions. 

And also, with the new update, you'll see that some champions, such as Valerie and Heiress, are marked as being required for a fusion. That means that sooner or later you will need to fully ascend them and level them at least to the required level for the fusion. If you figure their skills look useful for you now, you might as well level and ascend them now and use them for a while, then when you get better replacements you put them in the vault until you're ready for the fusion.