mystery files in All My Files I have a brand new MacBook Air, have not saved any files to it yet.  But I just noticed there are files in AllMyFiles dating back to 1997.  Are they "borrowed" from the iCloud?  Although they are not arranged in folders like in the iCloud, the ones I have opened are also  in iCloud.
You can answer this question for yourself. In the All My Files view, right click one of the files and choose Get Info. The window which opens when you do that has a Where: field. For a file in iCloud, the Where: field says iCloud Drive.