My question is, why mix the live action with the CG main character?

The other androids have human faces matched with CG bodies, why didn't Alita have the same?

Or why is Alita the only CG character and the other actors performances are filmed?

This movie is in some weird shaky ground where it's neither CG cartoon or live action movie, when the story might work better if it were either of the two.

Maybe the technology powering Alita seemed promising in pre-production and so the production moved forward with the filmmakers thinking the CG techniques could be perfected over the length of the production?

Also, is the source material basically YA? For some reason when the news dropped that this was being made, when Cameron was attached, it seemed that the graphic novel this is based on (?) was darker than the tone that was described in this trailer. Rodriquez and the producers can do whatever they want with the original story but this just seemed geared towards 13-year olds in the same way that Avatar was. The way the pre-production press told it, this movie was going to be more graphic and dramatic.