The disk is the physical object (noun) though. While 'save' isn't tangible, what you are saving to (a disk somewhere) is, which makes it real and easy to understand. When floppy disks truly disappear the icon will have to change. 'Share' might be about people but there's 1000 ways to interact with people, so you need to actually describe better what you are sending to people (a link, permanent access, everything you own, or what?).