It's quite the fun concept, but the only reason the game is playable is because the small units have no cooldown. Between creating multiple copies of the smallest dudes at once, their complete lack of any cooldown or penalty for using them, lack of power-to-cost on the small dudes, the fact that there are not hotkeys can almost be ignored.
But all those monsters look cool, and it's only realistic to bother with one because there's no way I'm going to be able to exert a meaningful presence on the map and keep on top of cooldowns on all my things. If you are going to develop this game more, hotkeys will not be optional- I like the concept and you've outright said it's a prototype, so I'm willing to allow some leeway.
Seriously, though. Hotkeys.