"These are rules for a language. And there obviously is NO creativity involved, it's just a compilation of facts about the language."
The 'facts' about the languages are not rules. The facts are the observation that a given word is spelled, mostly, at a certain point in time, a certain way, after that people invent 'rules' - usually with 'exceptions' - to codify that...
creating rules out of facts is creative. otherwise no scientific publication would be copyrightable either.