Nope, the site is not a WordPress site – it’s a good old-fashioned hand-coded site.
Anyway, I figured out what the problem was! Turns out that my site was moved from fud.dreamhost.com to wario.dreamhost.com; but all of my files were still present on fud and my login/password remained the same.
So it turns out that the original post was technically correct (that the path was different), but because I was using FTP on my end and checking the results in the browser, I couldn’t see the problem.
It wasn’t until my login on fud went dead and I noticed wario in the panel that I thought to log into wario.
Thanks so much for your assistance, everyone!