I can just see those fans complaining that the human cast is to huge to add to it already.  

What one might not understand is that the human cast is going to be gianormous, everybody from stars, extras, background, people getting squished, running like extras in a Godzilla movie, and stunt men/women.

Especially if there's scenes involving cities and the military included.

With over a 100 billion humans of Earth, it's not like it's going to be completely devoid of life on screen. Well at least until giant robots start fighting, then see how fast people disappear. RUUUUUUN!!!!!