The Bark Bites Back at 2012-03-09 10:22:36:
I agree. 6,000,000 is a number - not a name, nor a face.
By giving her a shade of red, we're drawn to her because she stands out in what would otherwise be a faceless sea of inhumanity. She gives it a face, albeit briefly. The fact that she's young implies innocence, something that also symbolizes the many victims.
It also demonstrates the power of narrative perspective. We're essentially watching her through the eyes of Oskar. We see her, we cut back to his reaction. We see her again, Oskar perched atop his horse, seemingly helpless as the violence happens all around him.
Her escape seems to imply hope, but really this is all to set up the reveal later that she in fact, perished. If she had not stood out at that moment, her corpse would have been just another among thousands.
When Oskar does see her again, it resonates thematically because we can see the regret that is echoed at the end: I could have gotten one more person...