RandomSquid
Steampunker
People seem very keen to point out holes in this, but all of the supposed holes are quite easy to patch without contradicting this lore in any way.
1. How do the corruption, the crimson, and the hallow serve balance?
First, remember that balance here means "fairness for all living creatures", not balance between light and dark or good and evil or order and chaos.
The corruption and crimson both exploit a loophole in this definition. The corruption, eventually, snuffs out life, which does result in fairness for all living creatures: with no living creatures left, there's nothing to be unfair to, and in the meantime it causes pain to balance out joy. The crimson, meanwhile, assimilates all other life, which will again result in fairness: with only one being, the world must be fair. The hallow is fair and kind to all of its creatures; and therefore it is its duty to spread and overtake the less-fair areas. The dryad sees the hallow as good because it cannot be overtaken by corruption or crimson and is a safe place, in the sense that NPCs can live there and therefore carve out a little patch of security.
2. Why does killing the guide summon the guardian of the world?
The wall of flesh is friends with the guide, so when you kill him with a voodoo doll it gets mad and comes to beat the snot out of you
3. How is skeletron supposed to be part of cthulhu, it's the wrong scale with the eyes and brain?
It's not. Skeletron is its own thing; the part of cthulhu's skeleton that was ripped out was its spine, which became the eater of worlds. Skeletron prime was created as a test, based on the original skeletron.
4. Why does killing the lunatic cultist summon the lunar events?
With his dying words, he calls out to the celestial creatures, knowing they'll invade, as a final act of spite.
5. What's the deal with the moon lord?
He's not cthulhu, but he's something eldritch nonetheless.
6. No indication of the importance/role of dungeon, clothier, mechanic, dryad, etc.
The dungeon is already a mysterious place, and the idea that it was a city is pretty well supported by the sheer amount of furniture inside. The clothier/old man doesn't remember much of being cursed; the mechanic doesn't see fit to mention her role in the creation of the mechanical bosses, but she's the only logical one to do so: the mechanical bosses are far from steampunk, and goblin technology seems to be rather improvised. The dryad mentions being ancient, and she probably considers the whole cthulhu thing something of a sore subject considering her family and friends all died in the process.
7. Doesn't mention the lihzahrds, the jungle temple, or plantera, even though they are very important
The lihzahrds seem to be rather isolationist: when cthulhu ravaged the world, they sealed themselves in their nigh-indestructible temple. The only reason the cultists don't appear until after you've fought golem is to preserve the boss progression; contrary to what seems to be a popular belief, the mysterious tablet doesn't come from the temple. Plantera is a legitimate mystery, but she may just be a natural part of the jungle.
1. How do the corruption, the crimson, and the hallow serve balance?
First, remember that balance here means "fairness for all living creatures", not balance between light and dark or good and evil or order and chaos.
The corruption and crimson both exploit a loophole in this definition. The corruption, eventually, snuffs out life, which does result in fairness for all living creatures: with no living creatures left, there's nothing to be unfair to, and in the meantime it causes pain to balance out joy. The crimson, meanwhile, assimilates all other life, which will again result in fairness: with only one being, the world must be fair. The hallow is fair and kind to all of its creatures; and therefore it is its duty to spread and overtake the less-fair areas. The dryad sees the hallow as good because it cannot be overtaken by corruption or crimson and is a safe place, in the sense that NPCs can live there and therefore carve out a little patch of security.
2. Why does killing the guide summon the guardian of the world?
The wall of flesh is friends with the guide, so when you kill him with a voodoo doll it gets mad and comes to beat the snot out of you
3. How is skeletron supposed to be part of cthulhu, it's the wrong scale with the eyes and brain?
It's not. Skeletron is its own thing; the part of cthulhu's skeleton that was ripped out was its spine, which became the eater of worlds. Skeletron prime was created as a test, based on the original skeletron.
4. Why does killing the lunatic cultist summon the lunar events?
With his dying words, he calls out to the celestial creatures, knowing they'll invade, as a final act of spite.
5. What's the deal with the moon lord?
He's not cthulhu, but he's something eldritch nonetheless.
6. No indication of the importance/role of dungeon, clothier, mechanic, dryad, etc.
The dungeon is already a mysterious place, and the idea that it was a city is pretty well supported by the sheer amount of furniture inside. The clothier/old man doesn't remember much of being cursed; the mechanic doesn't see fit to mention her role in the creation of the mechanical bosses, but she's the only logical one to do so: the mechanical bosses are far from steampunk, and goblin technology seems to be rather improvised. The dryad mentions being ancient, and she probably considers the whole cthulhu thing something of a sore subject considering her family and friends all died in the process.
7. Doesn't mention the lihzahrds, the jungle temple, or plantera, even though they are very important
The lihzahrds seem to be rather isolationist: when cthulhu ravaged the world, they sealed themselves in their nigh-indestructible temple. The only reason the cultists don't appear until after you've fought golem is to preserve the boss progression; contrary to what seems to be a popular belief, the mysterious tablet doesn't come from the temple. Plantera is a legitimate mystery, but she may just be a natural part of the jungle.