Is King Ghidorah a mutation?

It's called world building, typically it helps make a movie better

I imagine that some of his origins may be elaborated on in the film proper.

Most likely

World building and spoiling the mystery are two different things. There's such a thing as over-explaining some things. All we need to know is King Ghidorah is a powerful entity from space that could cause our extinction--That's all we've ever needed to know to establish dramatic tension within the movie. I don't really care if he's a unique creature, an alien mutation or the Easter Bunny one day out of the year, nor is that particularly vital information.

MDK 2 (MinecraftDinoKaiju),
The rewrites Dougherty and Shields did were minimal. There's nothing to suggest they did complete rewrites, they just added some thing for sake of consistency:

The Total Film article said, "Dougherty and writing partner Shields have been able to some input into the next film, 'We did some rewrites on the script just to help carry certain themes across and to flesh out some of the characters.'"

This is par for the course in Hollywood. Many screenplays go through several rewrites from multiple screenwriters. The 2014 Godzilla film had 5 different screenwriters work on it, but only Max Borenstein was given credit. David S. Goyer worked on it as well and Drew Peirce was brought in to polish it after Borenstein finished. Then Frank Darabont came in to flesh out some of the character moments.

Well it sets up that more of them exist so it is important

Maybe if they want to set up future installments? But I don't think it's important to the immediate story. If they bring it up, okay, but I hope they maintain mystery to King Ghidorah's origins. We never really found out where he was from in the Showa series/Mothra trilogy and that's a far more interesting and ominous background than knowing too much about him. What we don't know is far more terrifying and lends credence to the myths behind him.

Well the showa Era and Mothra trilogy were not trying to be as grounded like the legendary trilogy need I remind you of flying godzilla in godzilla versus hedorah

But being grounded doesn't mean you have to sacrifice dramatic tension by over explaining things. That has nothing to do with it.

Did knowing ghidorahs origins in the heisei Era ruin the movie, how about biolante, or destroyah did knowing their origin ruin the movie?

I never said it would ruin the movie. I said it would harm the dramatic tension and take away from the mystery. But since you ask:

The Heisei King Ghidorah's origins have been criticized since 1991, so for many, yes--It put a significant dent in the film for quite a few fans and critics. If anything the Heisei monsters are the #1 most guilty for being over explained--Particularly Battra and SpaceGodzilla which many agree are the weakest films of the era.

Meanwhile, look at the original Alien. All we knew about the xenomorph was what we watched on-screen. Part of what made it terrifying was that it wasn't over explained--The mystery perpetuated its terror. Then Prometheus and Alien: Covenant come out around three decades later and piss off half the fan base with some really convoluted backstory. The fact is it never really needed to be explored and worked just fine as it was.

Does an origin story really matter? It's just a fictional character. Whether an origin story is told or not wouldn't matter since King Ghidorah is established as a monster with space origins later to be found in ice imprisonment, only to break free with existential crisis inbound. All that could be best achieved is theorizing what his role was on Earth. The monster's history, after all, does predate the human civilization by a significant degree, therefore information on said character could never be complete. I personally enjoy the mystery behind King Ghidorah - in similar case, much like how Michael Myers used to be. No needing to fix what's not broken.

Agreed.

Look, I'm sorry I started some controversy, but if we could get back on topic, that would be great. Thanks.

It's a debate. It's why forums exist. I don't think you even jump started it.

G. H. Man you are arguing whether or not it matters if ghidorah is a mutant which is not what the topic is about; the topic is about if ghidorah is a mutant so please let's get back on topic

It's still part of the topic, however. Trust me, if I find the topic is truly deviating I will adjust it or close it myself. :)

Fair enough

Ok, that's fair.

I don’t know if anyone else remembers this, but Michael Dougherty posted an image of a worm on Twitter around the time they started filming. It had a caption talking about worms apparently mutating in space and returning to earth with two heads. 

Wait was that a thing?

Resurgence No, that sounds fake. I could be wrong, though.

It's actually real I looked it up

I actually went through Michael Dougherty’s twitter and found the post. I was mistaken, it was a retweet from Discover Magazine. I remember someone else sharing it at the time thinking it may have pertained to Godzilla so that’s how I remembered it too.

Yeah I looked it up, it is pretty interesting