I’ve always loved the name Joy Boy because it sounds like a “child full of joy”. Well, maybe there is a reason for that name, English sounding words in One Piece 99% of the times mean exactly what they are saying like smiles or laugh tale.
I think Joy Boy was a kid. Well, I don’t mean a toddler but like around 16 maybe. And that’s why Roger laughed, because he found it amazing that a child was so wise and enlightening.
People with childlike spirit and strength have always been at the fore front of One Piece, maybe they all inherited the will of Joy Boy. So how could a child be so important?
I don’t know, maybe he wasn’t the King of the Ancient Kingdom, he was the prince, and like Oden, he left home early to travel the world and inspire people. He was so wise and so free that he inspired thousands of people around the world. And he was nicknamed “Joy Boy”.
Unfortunately, for some unknown reason he lost the battle of his Kingdom by some evil trickery the now “World Government” did back then.
His father died and Joy Boy did not have the strength to fight them all, but he died leaving secret messages and clues so that his will moves forward. He left something in the One Piece that was precious and useful to him, and might be precious and useful to whoever inherits his will.
A child with a will so powerful that 800 years later is still being passed down. If you think this is really crazy, wasn’t Luffy 17 when he left?
I think that’s why Roger laughed, because he was so inspired by this kid who was far and above the most free and enlightened person ever.
Theory by LookSWtco.