Site not rendering images

I've searched far and wide and cannot for the life of me figure this out.

### This issue affects

- [x] The site generated by GitHub Pages
- [ ] Building sites locally

### What did you do (e.g., steps to reproduce)

I have images and gifs in `/assets/visualizations/`, and attempt to use relative links to those images in a blog post.

The blog post in question is here: https://ddejohn.github.io/2021/08/20/life.html

The blog's repo is here: https://github.com/ddejohn/ddejohn.github.io

I've tried loads of things based on stackoverflow and github issues discussions. Nothing seems to work. I've tried setting `baseurl: ""` and I've tried relative links in my markdown with and without a leading `.` symbol. I'm at wit's end, it seems like everything I find on SO and here in various Jekyll issues say to do different things and I can't find the "magic" combination.

My current `_config.yml`:

```yaml
title: ddejohn/
email: ddejohn@pm.me
description: A blog wherein I write about programming, mathematics, and my personal projects.
github_username: ddejohn
linkedin_username: ddejohn

theme: minima
show_excerpts: true

plugins:
- jekyll-feed
```

### What did you expect to happen?

Images to display.

### What happened instead?

Images didn't display.