Hey,
It’s a case-sensitivity issue. I’m guessing the operating system on your computer (probably Windows) and the operating system running the itch.io website (probably Linux) handle casing differently. On windows “Achilles.jpg” and “achilles.jpg” are the same, but on Linux they refer to different files.
All you need to do is capitalize it to “Achilles.jpg” on the image tag. I changed the source code in my browser on a hunch since I noticed the other image filename was capitalized and it worked.