Don't get hug up on "invented". Ruth Asawa registered for (1956) and received US patent 185,504 on June 16, 1959 at the suggestion of her professor, Buckminster Fuller.

https://theartian.com/ruth-asawa-patent-collaboration/

Don't get hung up on "patent". You can't patent an idea, you patent a specific implementation of an idea.

The boy experimented to find the optimal parameters (height, width, angles) for load bearing of that earlier invention.

So, the result of his work would warrant a new patent, of course with reference to all earlier patents of which his work is an improvement.