I thought Jekyll just compiled the input files to html/css/js and created a static site?

Hugo, too? I hear Hugo is easier.

I haven't used either of them.

If Markdown formatting is enough for you, I would look into using a static site generator, like Hugo or Jekyll.

If you want to keep your existing content as static files but same website skeleton and layout instead of copying and editing files you'll copy one and create the layout template. Then content and new posts and pages can be generated from Markdown files. If you set up CI they won't need to run Hugo or what you're using, only push the Markdown files to your Git repository.

Whatever you want to do primarily depends on: Your formatting, styling, functionality, and interfacing needs for the editor, and what you're willing to use or invest for setup.

Hugo runs from a single binary. The source layout is reasonable. With a single layout the folder structure doesn't have to be complex.

I'm not very familiar with alternative [Markdown] static site generators.

Maybe look at Astro and develop a lightweight blog post admin panel to create, edit, and delete posts. Should be relatively easy and you should be able to render out a static site from it each time you need to update it.