Do you know of any way to download and truly update back to pre-iTunes 12 iTunes apps for OSX?
If the question is can one revert to an earlier version of iTunes, then the answer is
yes*.
As wary of links myself, I will not provide any. However doing a simple search for this topic will return a lot of applicable advice. One site I discovered—AoxoA,
Downgrade Or Revert From ITunes 12 To ITunes 10.7—seems to cover this process fairly well.
Although I would recommend iTunes 10.7, some may wish only an incremental step back from iTunes 12 point something or other—and that is possible. This may also be a good time to mention that newer versions of iTunes will have features you may or not wish to do without.
One caveat (and why the asterisk on 'yes') is that reverting to a version of iTunes earlier than that originally installed on your Mac may either be impossible or prove problematic for some reason. As always the case, best to back up your system before proceeding; worst case scenario then is you'll just end up back where you started.
Apple in their warped wisdom doesn't make such a process simple, so you need to be your own IT department on this one. Nevertheless the steps are fairly straightforward and easy, once you know them. You'll also likely need to assemble a few software tools like Pacifist to best accomplish this.
For some reason I do not recall now I once suffered the unimaginable in inadvertently 'upgrading' to a newer version of iTunes. As that would never do I did some research and accomplished what you possibly have in mind—or back to iTunes 10.7, as myself and the Gods (if not Apple) intended. If this on a 2012 MacBook Pro, so software it was already familiar with and natively ran. So it IS possible. Although, as said, individual results may vary, depending.
All best luck in having the Apple experience you desire.