After the confirmation Joyboy was the first pirate, I felt compelled to put this together.
We can assume Shanks told the Gorosei what it seems to be the information about Blackbeard special lineage. Now, it must be something really shocking and important. It can’t be something as simple as descending from an obscure figure like Davy Jones or a character we haven’t heard anything from, the set up is non existant.
This info was dropped after we learned about the Buccaneers and we finally got the three races Big Mom lacked: Giants, Lunarians and Buccaneers. But why all the fuss about concealing this info? Kuma is already a Buccaneer, and I don’t think Devon or Augur would look at simply his race as being that relevant.
The answer is straightforward: Blackbeard’s lineage is that of Joyboy’s.
We know both inherited will and genetics are important in the series, and as they work independently we have lots of characters that embody different wills from different lineages, from Roger and Ace, to Joyboy and Luffy. But what about Joyboy’s genetics? Wouldn’t make sense for Luffy’s other side of the coin to hold the other side of what made Joyboy himself?
This would explain a couple of things, like the Blackbeard Pirates devotion for his captain or Imu stabbing Blackbeard’s poster. Why would he single out Blackbeard? It’s not just because he’s a D, there are multiple of them, why not stab all the posters of all the Ds? As long as no one knows what the D is, it’s just a letter.
Maybe it’s just the possession of the darkness fruit, which might be more significant down the line. But I will wager it’s because he looks exactly like Joyboy (or at least similar to him), the same way Vivi looks like Lily.
That could also explain Blackbeard’s weird body and its interactions with devil fruits, because he has the lineage of the most powerful Buccaneer that existed.
With all the focus about how the Buccaneers are extra tough, the fact that they can take well a beating and how they are some sort of hybrids between humans and giants, would it be enough if Kuma was really the only alive one? Why did Devon and Augur come to the arc to drop the line of Blackbeard’s lineage, if not because it’s all tied to one of the main villains?
Even the fact he doesn’t sleep could be explained by being one of Joyboy’s special traits. After all, Shanks speculates it would be fun to not sleep.
Or as T.E. Lawrence, an archaelogist, Blackbeard’s job in the real world said:
Speaking of archaelogy, this would also help to explain why Blackbeard is so knowledgeable about absolutely everything in the series. He most likely inherited some physical evidence, or maybe just some bedtime stories.
This would also make Shanks and Blackbeard mirror even more heavily: One a descendant of one of the ancient kings. The other the descendant of Joyboy. Both now on the opposite moral ground.
With Joyboy being the first pirate, it just seems fitting Blackbeard is the ultimate, most accurate pirate, and his defeat will close the circle and mark the ending of pirates, as we understand them irl, with only pure adventurers remaining, like Joyboy, like Luffy.
Theory by GoldenSaturos (https://www.reddit.com/user/GoldenSaturos)
