[SPOILER] Plot Discussion Thread *Spoiler Alert*

[Xenomorph]

So I rewatched the ending. Essentially you are the last lifeforce of the machine that it needs to keep working. When you deactivate the machine an kill yourself, you are ending the machine for good. The pigs singing out and eventually fall silent, this is due to the fact that they were connected to the machine so without it they can no longer go on living. You live in a sort of silent purgatory with the two entities of yourself, freed from the machine.

So you do "cleanse" yourself and everything you've done. The machine slowly falls silent and everything is undone as the new age begins.