It is obviously too young to fly and you are concerned. When you approach the young one, several adult crows swoop down on you with loud and aggressive squawking. No birds of crow size learn to fly while in the nest. They can be on the ground for periods of up to a week, not only learning to feed, but developing the muscle strength and coordination to gain flight. The attacking crows are the parents, dutifully letting you know of their presence and capabilities.
Nothing can raise a baby crow as well as an adult crow.
You see a young robin walking around your front yard with one of its wings dragging behind it on the ground. Both of its parents are nearby and are still feeding the young bird. While wild animals are very competent parents, they have yet to learn how to apply the principles of medicine. Any bird with a fractured wing, a dragging leg, or a visible wound, requires immediate help. Cat saliva contains bacteria that can be fatal to wildlife.