This was the missing piece of information: "If you change the extensions of the files as ".qvf" they would become importable."
For others who want to backup only the apps and recover from a backed up app:
1. Backup the App folder which is located in Shared Content Folder.
2. The apps from the above folder are named with the app's IDs. To identify what ID has the app you want to recover, go to HUB -> Monitoring Apps -> Operations Monitor -> Apps and search the name of the app in the "App details" section.
3. To recover the app:
a) go to your backed up version of the apps folder
b) copy the file with the ID you just discovered at step 2
c) paste it to another location and rename it with the extension "qvf" (i.e. if the name is "ifhgd-ih2-34jk-ijt34kjk", rename it to "ifhgd-ih2-34jk-ijt34kjk.qvf")
d) import the renamed file by going in the QMC -> Apps, click Import and choose the renamed file