Mythology tags are currently set to the tag type Copyright. ^{List of mythology tags.}
Holiday tags are also currently set to the tag type Copyright. ^{Partial list of holiday tags 1, 2, 3, 4, 5}

This is inconsistent with how the Copyright tag type is used in all other cases. According to the wiki article on tag types:

"A copyright tag is for the program or series a copyrighted character was first featured in, like Renamon in Digimon or pikachu in Pokémon. It can also be used for the company that owns a program or series, like Disney owns the copyright to Mickey Mouse and Nintendo owns the Mario Bros series."

Mythologies and holidays do not entail copyrighted characters or media companies, so the copyright tag type should not be applied.

Should these two groups of tags be changed to the General tag group?

My personal reason for wanting to change the tag type to general is that I use "copytags:0" to search for art not featuring tv/movie/game characters and the current situation excludes all art containing mythological themes and holiday themes.

-1. They need to stand out somehow, and Copyright is far more fitting than General. You can run a search for something like Christmas copytags:1 to get around the problem to your personal preference.

Caroway said:
Mythology tags are currently set to the tag type Copyright. ^{List of mythology tags.}
Holiday tags are also currently set to the tag type Copyright. ^{Partial list of holiday tags 1, 2, 3, 4, 5}

This is inconsistent with how the Copyright tag type is used in all other cases. According to the wiki article on tag types:
Mythologies and holidays do not entail copyrighted characters or media companies, so the copyright tag type should not be applied.

Should these two groups of tags be changed to the General tag group?

My personal reason for wanting to change the tag type to general is that I use "copytags:0" to search for art not featuring tv/movie/game characters and the current situation excludes all art containing mythological themes and holiday themes.

-1
it acts like a brand with united features, colors, characters, and themes. Let's keep it where we keep the branding.