@amlilui I think that you're on point with showing the character up close and wanting to emphasize how high they are swinging.
I actually like the "boring" composition the best because for me it tells the best story. I feel you can omit the framed structure of the swing and just show the swing coming in from the top. I would also keep the horizon line very low to emphasize the height.
I really like the idea of adding a grasshopper through the book! It's quite a popular trend and kids would love to look for it on every page.
Here are some Pinterest links I liked which can hopefully help you with the composition:
https://pin.it/6YhtWH6
https://pin.it/3bdXmEK
https://pin.it/5cGNjxn
https://pin.it/oasuXXf
Some of the characters in the references are turned away, but I think it would be nice to have them face the camera so that you can see their expressions.