This is a young fox, around 5 months old. At this age they are extremely curious and a lot bolder than adult foxes as they start to explore the world on their own. They haven’t yet fully learned what is and isn’t dangerous so are more likely to approach humans if they haven’t already had negative experiences with them. Fox mortality is at it’s highest between 5 months - a year, partially because their lack of caution means they’re more likely to get themselves into dangerous situations.
The way this fox is acting looks like it’s never encountered a human before (or at least not one lying down) and is very interested in this strange new creature. Because the man is lying on the ground he will appear less threatening to the fox. The fox is still showing some wariness, which is good, and suggests it hasn’t been tamed by people. The fox also seems very interested in the sound of the camera shutter and may be checking it out to see if it’s a potential prey animal. The man also isn’t trying to lure the fox close with food, so this is just natural curiosity.