I am smitten with this image and woke up thinking I should jot down my thoughts for others to read out of concern that others may tend to overlook this shot.
We have the dynamic of diagonals, both in lines and in balance, but those diagonals are opposed! which makes them even more dynamic. We see a child's feet which are in motion-blur, just enough blur, but not so much that it loses definition. The "off-stride" kicking lends an air of human interest.
The child's feet might be a mystery if it were not for the shadow which illustrates what is happening. The shadow is oddly somewhat less blurry than the feet, and is about as well-defined as shadows ever are on rough ground.
The tilted frame is a perfect example of when a tilted frame actually helps a photograph, because in this shot it actually accentuates the motion of swinging.
The B&W conversion is the perfect choice for presentation because it serves to emphasize form, line, texture, balance, and intrigue possibly in a way that the color version would not do as well.