I've been using using iTunes since version one dot nothing, when it was an Mac OS 9 -only app. And I used the program that Apple bought (called SoundJam MP by Casady & Greene) and turned into iTunes. It's you who do not seem to understand how to use iTunes... 🙂
In current iTunes, navigation revolves around the horizontal bar that goes across iTunes window. If you want it to look and feel like old iTunes, at the left end of horizontal bar, click the Music button to show your music library. Near the middle of horizontal bar, click Playlists; the sidebar appears along left side of window. At the right end of horizontal bar, click the control to change the view to Songs; the music library is shown as a simple list, with columns. There are no "layers" and nothing is "steering" you except for your imagination.
If you are referring to Apple Music, it does not "hijack" your song files that are stored on your computer's drive. The iCloud Music Library is an additional service that allows you to access your library on other associated computers and devices that you own. It does not alter your original files stored on your Mac, unless you do something like delete those files intentionally. Keep and back up your original files, like you did before Apple Music.
If you show your iTunes window like I described above, it's not that different from the original iTunes window when iTunes only supported audio files. As more and more features were added to iTunes, such as iPod support, iTunes Store, podcasts, audiobooks, videos, apps, etc., it became a convoluted experience, especially for brand new users. Version 11 was an attempt to re-design it - not well done (but you could set it to look and work mostly like the previous version). Version 12 is better. It removes the clutter while keeping the familiar (like the sidebar that appears when needed and useful).
the scrubbing bar has disappeared
It's along the bottom edge of the Now Playing box, at the top of the window.
the repeat song button is buried
From the menu bar, Controls -> Repeat -> One. That's one action. It may be out of sight, but hardly "buried."
Apple user since the original Mac.
The need to convince others of being a "long time Apple fan" is quite telling... 😉