Owned vs Purchased music.

You never lose rights to purchased music. And to be clear, you never OWN music. You get rights to play it under certain conditions for eternity. Not the same as ownership.

The "copies" that Apple places in your iCloud Music lIbrary do have DRM attached, and never belong to you like an iTunes purchased or CDROM based music track.

Sp, while you are a subscriber, you don't have "ownership" of your files. after you stop paying, you go BACK to your DRM free files, which you still don't actually own..

You are fully responsible for backing up your NON-DRM copies in the event you stop using Apple Music. That is, all the music you had before you started using Apple Music.

Before you subscribed to Apple Music, you digitized your CD based music and were using it on an Apple device according to terms you agreed to when you bought the CD. Let's call the file you created this way file A. In Apple terms, there is no DRM attached to file A. Apple never imposed additional restrictions on your usage as the assumption is the right on the CD are still in play.

When you enabled Apple Music, Apple substituted your file A with their DRM protected file B.

Same music, same artist. Different rights for you. Rights enforced by Apple on behalf of the rights holder/artist.

Using file B while a subscriber, your usage of file B is limited to devices that are authenticated with Apple at the time. Personal usage only, etc.

If and when you leave Apple Music, you go back to file A and the broader rights you have wit that file.

Hope that's clearer. I am not Apple, nor an IP lawyer, so feel free to dismiss my version of things.

Does Apple assume any rights to such music when stored on Apple servers?

No. The rights holder, typically the artist does. Apple hosts the content and licenses it you on their behalf.

Does DRM give any legal rights to the purchaser other than the right to listen to it?

No.

Why is it necessary to digest a legal contract to understand or comprehend the users‘s rights?

Ask the artists.

This has been around since 78s and 45s. In those days these rights were easy to enforce as nobody could easily make copies of vinyl records. Until the late 60s and early 70s, the technology to bypass DRM simply didn't exist or was prohibitively expensive.

Cassette mixtapes in the 80s/90s and forward made it something artists had to enforce. If you look at the fine print on a 45, you likely will see the artist stating their rights to you. LP liner notes, CD liner notes. The lack of technology to reproduce the music made the declarations of rights mostly moot for a long time.

The concept of "not" owning the music you purchase is not new. You never get title to music.