As I coach, I've seen kids who fit the "gymnast" bill who struggle with body awareness and the ability to learn skills and I've seen kids who don't fit the stereotypical criteria do pretty darn well. So many factors come into play in terms of a gymnasts ability, and while build and innate ability are definitely among those factors, they come in many forms. I've seen overweight children with remarkable flexibility and kids with a short/muscular build who have no idea how to tap into their strength. It's silly to pigeon hole a kid for the way they are build, especially when they are 5.
As a gymnast, I was average height and very "dense"- the type you would except to be a power gymnast. And while I was a good tumbler, I struggled terribly with vault and typically got my highest scores on bars. So much for that stereotype. And look at McKayla Maroney, she's a skinny string-bean type gymnast and is remarkably powerful, the best vaulter in the world! Just try to ignore those busy-body parents and have fun watching your DD enjoy her sport!