That is not a contradiction. There will be plenty of non-humanoid chieftains.
Regarding the humanoid races:
I really would like to do more work on them, but I've run pretty much out of ideas now. For elves and gnomes, I had a lot planned long before, so that was relatively easy.
With the other races, I am still at a quite early point. So maybe some of you have ideas that might help me get on track and find their own niches and cultures?
For Lizardfolk, my primary reference are the Jungle Trolls from Warcraft. I actually started out with trolls, but wanted something more generic and lizardfolk quite the whole thing quite well.
The Kaas are a logical next step in the development of orcs away from the murdering monster origins. The Warcraft 3 orcs are not quite bad, but the major reference are the Maltak orcs from the webcomic Dominic Deegan. Though they are bit strong on the noble savage line. Also Qunari from Dragon Age 2, those guys are awsome. And also the Cathar from Knights of Old Republic, where I got the name from.
For the tree critter race, I still don't have a good name, and I hate to start working with placeholder names. They are a bit like Baldur's Gate style kobolds and a bit like nezumi (rat people). Quite energetic and daring, but not silly or stupid. They have great racial bonuses to climb, jump, and balance and for standing just 5 feet tall they are quite quick. Which makes them extremely good at foot chases. Their society is the most simple and they live in huts in the forests, but those who mingle with the other races are smart enough to adapt to civilization easily.