The only secondary possibility is that the second h only is silent. In response to your question go do a historical study on Cthulhu. I have and don’t care to teach a class on it LOL.
Edit: copyright infringement with owners of HP Lovecraft short story “The Call of Cthulhu”. However Lovecraft did NOT invent the word Cthulhu per say…it is based on Ancient Greek. He did invent the mythos of Cthulhu.
That should be common knowledge tbh
The name Cthulhu is present in terraria lore, with no problems
Metallica probably named the previously mentioned song that way because they felt like it
they tend to do that
public domain basically means that you don't have to credit the creator and won't get struck down for using whatever it is that they made that you wanna use
basically nobody 'owns' it anymore, like communism but for art and also 1000 times better.
It basically means that "no one legally owns it anymore", whether due to no one legally owning it to begin with, or a variety of other reasons. People can use it for their own creative content, though there are restrictions of course.
In most countries, copyright protection expires 70 years after the death of the author, and H.P. Lovecraft died 85 years ago, so it enters "public domain".