Now, obvliously, the content may contain personal data, or possibly be personal data (if it's pictures of people) and in that case I assume it would be covered.
I'm not convinced your interpretation is correct. GDPR Article 4[1] states that "personal data" means "any information relating to an identified or identifiable natural person (‘data subject’)", so it covers anything you produce that's somehow related to you.
In theory even the personal writing style might be considered "personal" as it could be used to identify individuals, but I don't think that lawmakers thought that far.
I could be wrong (i'm no expert) but i remember part of the GDPR is about "data portability" and is exactly that: you should easily be able to export all the data you've provided. https://gdpr-info.eu/art-20-gdpr/
I would assume this includes articles you've written.
Now, obvliously, the content may contain personal data, or possibly be personal data (if it's pictures of people) and in that case I assume it would be covered.