to answer your edit, yes all creatures started out as single celled-organisms many billions of years ago and gradually evolved. this process is still happening today but takes millions of years, not something you would observe in a human lifetime
definitely watch it with them. just faking it will only get you so far before the act falls apart. it'll also help you build your relationship with them if you show interest in picking up and learning stuff she likes IMO
figure out how far up before you stop washing your face