Poor girl! Shame on those adults for penning her out in a kennel her whole life. Thank goodness you got her and are giving her a first real home. Sounds like due to a lack of proper socialization and training, she has a mild case of shyness. More exteme shyness usually shows as fear aggression. In fact, she might just be adjusting to her new, improved environment and will get much less shy on her own within a few weeks.
This article may give you some ideas to help bring Calli out of her shell. In general, you'll want to slowly introduce her to lots of different sights, sounds, and places. A good basic obedience class should also help with her shyness and build a strong bond between you.
Shy Dogs: Answers to Frequently Asked Questions
Looking forward to reading more stories about you and Calli!