So obviously Yuumi is a non- humanoid character and honestly I like her design a lot. As someone who played a ton of Abathur and duo'd as Gall with my friend being Cho in HotS, I'm extremely excited for the kind of gameplay Yuumi provides. That being said, I've also been a big fan of monster champions over the years and there basically hasn't been a new one since Aurelion Sol. If you want a monster to actually be monstrous, you'd have to go back even further to Rek'sai.
Now I get it, monsters don't sell as well as humanoids and they're also kinda wonky to balance because their weird proportions are usually matched with weird kits, but I think we're overdue for a new monster. Lots of people thought Pyke would be a sea monster, the wording of Kayn's teaser could be construed as a monster, etc. I like both of those characters too, but I do wish one of these times we'll actually get something horrifying especially with all the new Void art.
Basically, when Reav3 said a non- humanoid was being made I'm sure lots of people thought of monsters. Yuumi's going to be my enchanter of choice from now on, but I'm still patiently waiting for a high quality abomination to come out. I think enough time has passed to give us one, monsters may not be super popular but the small playerbases they gain are super dedicated and honestly it's cool to fight alongside one even if you aren't the player. Whenever I see a Vel'Koz on my team it's just fun to watch them move and cast spells, it makes the game world feel like more than humans in various cosplays.
Riot could also update Skarner or Cho'gath so our existing monsters are even more spooky. I'm just beginning to worry the content draught for this type of character design is actually indication we'll never get a monstrous non-humanoid again.