As Keith helped her to figure out how to use the phone camera, Apryl learned more about humans that added to the level of confusion that she already had about them. Their lives really were far more complicated compared to those of werewolves who lived as wolves.
For one, thumbs were far more necessary in the life of a human than she would have liked. Wolves never had the need for such things as they most just relied upon their teeth or claws to help them out. In a similar fashion, humans seemed to need their thumbs to help them get certain tasks done. Apryl determined that without the opposable thumbs, humans would likely be doomed.
Thumbs were what helped the female werewolf to try and steady the phone properly after Keith had given her a few demonstrations on exactly how to use the thing. She was still rather confused by it all, but somehow managed to hold it steady so she could focus it to take a picture.