Joyboy made a promise to the sea goddess Poseidon.
Davy Jones (the most notable appearance of his is from POTC) has a thing with the sea goddess Clypso.
Joyboy in OP is the first pirate in history, Davy D. Jones made the Davy Back fights.
Joyboy is pretty huge in size, Bucaneer for sure. And coincidently a "bucaneer" and "davy clan" were the prize together at God Valley...
Xebec's father here is a huge dude who also wears the strawhat. And could pass for a bucaneer size, or atleast a mix.
Saturn claimed the Bucaneers committed a grave sin or w.e and they was born to be slaves. Then in Harald's flashback we get similar statement to the Davy Clan.
World Government doesn't care about the "Monkey" "Trafalgar" "Gol" "Portgus" but the "D." part in the said names... For Davy, it's not the same situation, they don't fuck with the name "Davy".
Davy Clan's sin, the reason Imu hates them so much, is because they're descendants of Joyboy.
Bucaneer's sin, the reason they're hunted so much, is they're the race that Joyboy belonged to.
It's not Davy Jones vs Joyboy or some light vs dark shit. It's Davy D. Jones = Joyboy. Xebec and Teach are the direct descendants of Joyboy.
Similarly "Blackbeard" is Marshall D. Teach/ Davy D. Teach... Not Marshall D. Blackbeard. Joyboy is similarly simply the nickname akin to Whitebeard/Blackbeard are.