There's a case to be made, realistically speaking, that using a well-known framework or even a CMS like Wordpress means less complexity specific to your website to understand for the next person. FTP cough SFTP or Markdown/HTML is definitely not beyond non-technical people to understand and use, but sadly there could be some resistance nowadays I imagine.

I would look into static website generators. Sadly I'm not sure what is most reliable nowadays, but I would prioritize easy of use and installation, as speed is probably meaningless on your scale. Here's a random article.