Modern Mac folders: “Library comes only from the Data volume, … in the path Library/Apple/System/Library are some components that should appear in the main System/Library.”

Link. Browsing these folders is like exploring Rome — modern atop ancient.

“There are two places that mounted volumes are listed in the Finder: the hidden top-level folder Volumes, where Macintosh HD is just a link back to the root complete with its merged volumes, and in System/Volumes, where what’s shown as Macintosh HD is in fact not the merged volumes, but only the Data volume”