Curate
Curate is where playlists live, along with Discover, which offers shelves of things to play next, drawn only from your library.
Playlists
Create a playlist, drop tracks in, reorder them. The same song can appear twice. Export to m3u8 when you need the list somewhere else.
My Favorites sits at the top of the rail. It is a view over songs you have hearted, not a playlist you can accidentally delete.
Star a playlist or an artist to pin them in the Quick Menu on Now Playing.
Discover
Discover is not a recommendation engine in the streaming sense. It is a page of named recipes over your files and your listening log: unplayed records, a discography you have barely started, something you loved and forgot.
Each card has a one-line reason. A shelf is not a playlist until you save it as one, and nothing here leaves your machine.
The queue
Up next is two layers: what you queued by hand, sitting above the rest of the session you started. Shuffle reorders the session, not the tracks you put there on purpose. The queue itself is for this sitting; playlists are what you keep.