Many children can understand what a metaphor is...as in the geek who is the "PC" represents the idea that those are the only types of people who use PC's.
Apparently your understanding of the ad is that a PC is literally a geeky human and a Mac is literally a cool human. You must have a heck of a time when you try and use a computer "joystick".
That would also, by the way, be the intent of the creators of the ad. Thus the sentence "I'm a PC." The actor is a metaphor for a PC running Windows.