I have a better theory for "planet Minecraft": Since you don't observe any curvature on the surface of the theoretical Minecraft planet, it must be very large. We also have another question: What do the various seeds of the Minecraft world all depict? Does each of them represent a different planet? I'd say they're all part of one huge planet, with each world surrounded by a "fence" that limits each player to an allotted plot of land of a given size. After some calculations, the area of all possible Minecraft worlds comes out to be 7.5557864e+34m2, which is equivalent to a sphere with a radius of 77541626063248km, or roughly 8.196 light years. Given the void beneath the bedrock, we can assume that this massive planet is hollow and is essentially a giant spherical shell, with a massive core floating in the middle of this void. Around the very dense planetary core is another floating layer of roughly 1/8 the radius of the outer sphere, which is the Nether. A nether portal basically works as an elevator, transporting you between two corresponding points on the Overworld sphere and the Nether sphere. This also explains why the nether lets you travel faster since as you scale down the sphere, the distance between any two points on the sphere shrinks as well. Lastly, there is the End Islands belt, which has the same gravity as the Overworld and the Nether and is floating in the empty space between the Overworld's and Nether's bedrock crusts. If you think: well, this planet can't exist, planets like this can't form! And you are correct, this planet didn't form naturally. It's a former multi-level Dyson sphere, left behind by an ancient, now extinct civilization, existing around a former star, which collapsed into a black hole with a mass of 23 trillion suns (bigger than any in the known universe), which generates gravity for the inner layers of the Minecraft planet. Since the Overworld surface layer is too far from the black hole to experience any significant gravitational pull, a layer of equally spaced, dense celestial bodies (likely also engineered by our hyper-intelligent precursors) is introduced below the Overworld crust layer. And finally, on the topic of 'the planetary engineers', who are the two beings talking to us in the End Poem? We know they aren't the ancient builders, we know they aren't mobs or players. So what are they? They could very possibly be the last two surviving members of the 'planetary engineers' species.

And there you have it, a whole new theory for the planet Minecraft. Below is a visual representation of the theory. Might get a bit crazy here and there, but what theory doesn't sound crazy to some extent, right? I'd say that despite how crazy it sounds, it makes a bit more sense than the pre-1.19 theory by Austin. Feel free to poke holes in it tho, I'm sure I missed some things.