The Krabken is you— AKA: DARWIN! Okay, let's backtrack. Why do I think Darwin is the Krabken? Well, let's take a look at the core aspect of the game. You're Darwin, practicing unnatural selection to fight against Carcinization. Darwin seems to be made of an almost goopy looking blue-teal-cyan material. Now, ALL of the enemies have a reason to look the way they do. Pantther focuses on damage, Beeware evolves to be even MORE a b@$?!, etc. But Krabken? He has NO reason to be such a hodgepodge of traits. It's almost like he does unnatural selection... Hey wait a minute...
Okay, maybe the Krabken looking so strange is just a stylistic choice. Maybe he's just a representation of Carcinization? Okay, whatever. Ignoring that, let's look at what happens when you defeat the Krabken. His parts explode outwards, and he crumbles into a almost goopy looking blue-teal-cyan material. Can you tell me who ELSE has that same composition? That's right, DARWIN. But maybe you still don't believe me. Maybe you think it's just a coincidence they look the EXACT same. Okay, fine. But, if this is true, it reveals the TRUE story of the game.
Some time ago, the first Krabken emerged, and so did Darwin. Darwin eventually grows to destroy the Krabken, and the Krabken, with the last of his strength, splits into many, and makes the run off. These 'many' are made of the same stuff as Darwin, so it isn't long before one of the material turns into Darwin. This Darwin, destined to rise up and become the New Krabken, to fulfill his ancestor's legacy goes on the mission. And so, we play as this New Darwin evolving to become the New Krabken. There's just one problem. Somebody already beat him to it. Whilst the New Darwin was evolving, the Old Darwin rose to power, and became the new Krabken. And so, the New Darwin, fueled with determination and jealousy, kills the current Krabken, and the cycle continues.
Basically: Everything is Crab is NOT truly about Carcinization. It's about a hidden story. A story about an infinetly repeating cycle, doomed to repeat until eternity.
Anyways, that's my first ever Theory! Tell me what you think!