So to start I think we need to understand that in One Piece there have always been mentions of races but we havent gone too deep into the mention of clans. I think clans are ppl who decide to to assign themselves to a specific type of thinking. And the three main clans that I believe are the center of the one piece universe are the D clan, Imu’s clan (synonymous to the WG), and the Davy clan (i know this is technically the D clan but I will consider them separate for my theory so hear me out).
The D clan’s philosophy is to be free, merry, and uncaged, Imu’s clan philosophy is dominance (which I will equate to oligarchy later on), and the Davy clan’s philosophy is survival of the fittest or for the world to be ruled by strength.
So now referring to the Harley Text. I think each “world” refers to the current state of the world which ends when a clan comes into power to take control of the world with their philosophy. Although, in each instance of the worlds, the Sun God appeared to free the ppl in accordance to the D clan’s philosophy. Earth God is the head of the Davy Clan that I will explain later, Forest God is Imu or something that grants Imu power is the head of the Imu clan, Sun God is the head of the D clan, the people of the Full Moon are people directly from the moon, people of Half Moon of descendants of the moon that have mixed with humans on earth, and the voice of the fractured moon are now ppl of the D clan who don’t know their history but have the voice of all things.
In the first world the Davy clan won and ruled the world with its philosophy. I say this because in the Harley text it said the “Earth God was enraged and together with the serpent of infernal flames, shrouded the world in death and darkness”. Now I’m equating the Earth God to the Davy clan because of the reference to darkness (in other words Blackbeard’s darkness fruit) and death, which would be the chaos that resulted of the survival of the fittest. Also in the God Valley flashback, Rocks referred to Davy as the previous king of the world and Imu took offense to that probably because Imu thought the way the Davy clan’s philosophy ruled the world was abysmal. Mind you in this time I dont think there was much sea faring, so there wasnt much communication between ppl so it was easier for the Earth God to come into power.
So in the second world Joyboy, following the D clan’s philosophy, comes into play. Joyboy somehow acquires the power of the Sun God and becomes the first pirate. Along the way, Joyboy somehow encounters the Sea God because as the first pirate he was also the first sea farer. Joyboy and the then Sea God became friends and Joyboy promises that when he frees the world he will also get the Sea God and their people to communicate with everyone who lives on land and they can be happy go lucky. Imu comes into play and somehow acquires the power of the Forest God. Somewhere along the way, Joyboy meets Imu, from chapter 1181 we can tell that both were buddy buddy at some point, and they come up with a plan to usurp the Davy clan or the Earth God, so then they can come into power because the philosophy of the current ruler(s) just wasnt it. “The sun did nothing but spread the fires of war” this means that as Joyboy and Imu tried to amass enough military power to overthrow the current regime, war was inevitable as they had to get people under their flag. This was mainly driven by Imu as he follows dominance, but Joyboy was probably the face of the cause as ppl are drawn to him and Imu stayed in background doing his stuff which is synonymous to what he is doing in the Third World. So eventually Imu and Joyboy beat Davy, now it was time to understand which philosophy comes into power and here is where the civil war comes to play. “The Forest God sent forth demons” as we found out from chapter 1181, demons are people who desire power. Imu/Forest God promised power to the 20 kingdoms that sided with him against Joyboy and as a result they beat Joyboy. “The Sea God raged”, the sea god was pissed Joyboy was taken out, and that the surface world would not break bread with them and their people so they flooded the world to make make more area for their people to be free. But alsooo, Joyboy had contingency plans in the poneglyphs and the Sea God, where I think Joyboy told the Sea God that if in the instance he dies, to flood the world to allow for the next age of pirates, the next coming of him to find his inheritance, and to hide the passage to Laugh Tale (since Imu probably already knew where it was and would destroy it). The civil war eventually ends with Joyboy telling Imu that ppl will want to be free and his next coming will eventually come and the D clan philosophy will rule the world. Imu takes over establishes the celestial dragons per “humans slew the sun and became gods”, and establishes his oligarchy with his descendants and the WG ruling the world.
The Third World is where we are in now. “The troubled shadow hears the voice of the fractures moon”, is Imu being pressed that the D clan is coming back into power with its ability of the “voice of all things” to uncover the truth of the past, find the location of Laugh Tale, amass military power, and have its philosophy take over the world.
I say this all to say that Luffy’s dream = Joyboy’s dream = Sun God’s dream. Which is to have everyone (including people of Earth and the Moon) be free, exchange cultures, exchange sake cups, to share resources, party, and most important of all to stop war/fighting across countries (which is why luffy’s crew was so shocked and thought what he wanted was impossible).
I know there are holes in this, like who is “they”that will meet again? Maybe “they” refers to all of humanity as a whole who will meet together and break bread and be harmonious? Also the fact that Davy is technically part of the D clan as well, maybe there were different philosophies within the D clan? Idk
Tell me what you guys think