GH pages Jekyll Theme loads only partially

I’m new to Jekyll, have read the docs and tried troubleshooting, but I can’t get the theme I have chosen to display properly. The theme loads, but not all of the navigation is there, (Home shows, but About, CV, and ‘Recipes’ don’t show, and the home image doesn’t show. I thought it might be an URLs issue in some of the theme’s config, index, and style files, but I can’t find what’s wrong in which files. Forum searches here and on stack overflow have not yielded answers.

I thought that the easiest and fastest way to start would be to fork a theme, make it run on GitHub pages, and swap the original content out and add my own. But now, if that was true, I think I’ve lost whatever time advantage there might have been.

Can someone take a look or make any suggestions re: what I could do to make this theme work, or what I’ve done wrong?

Meanwhile, I will try this same method with another theme, and I will also try installing Jekyll.

My forked repo: