How to re-install iTunes (any version) on macOS Mojave?

Recently, my iTunes had been running sluggishly, especially when using Apple Music functionality. In the past, something I did which was often helpful when this happened was to completely uninstall iTunes on my Mac, then download and reinstall it fresh from Apple's website. As I had done in the past, I changed the "Sharing & Preferences" settings for iTunes so that I could delete it from my computer, and then deleted iTunes and all the associated system files.

However, now that I am going to reinstall iTunes, I see that macOS Mojave won't allow me to reinstall it at all?! I downloaded the iTunes 12.8 installer from Apple's site, and the installer states that "This update requires macOS version 10.13.99 or earlier". I also can't seem to find a way to reinstall the new 12.9 version via either the new Software Update feature, or via the App Store. This is ridiculous! Surely there is some way to get iTunes back on my computer. I don't need it to be an old version, in fact I'm perfectly happy with 12.9... I just need a way to put it back!