You are correct, there should not be an app needed to open a window for the Finder and package is definitely wrong for the kind.
Let's try this -
- In the Finder, go to the Finder menu and select Preferences...
- Go to the Sidebar tab.
- There should be a checkbox next to Desktop under Favorites and it should be checked. Un-check it.
- Close the Preferences dialog and restart the computer.
- Go back to the Finder Preferences the same way you got there before.
- Check that checkbox again, next to Desktop.
- Open up a new Finder window.
- See if double clicking on that folder works correctly now.
If that works, you should be good to go. If not, try this -
- In the Finder's Go menu, select Go to Folder.
- In the resulting dialog type (or copy and paste) ~/YourUserName/Desktop - replacing YourUserName with your actual username.
- Go to the File menu (without clicking on anything else) and do Get Info... again.
- Report back with what it says here.
This is an unusual problem you have. Keep us up with it, we'll continue to work with you.
Are you able to go to your Home folder and see its contents (which should contain the Desktop folder?)
Does the Desktop folder look like a folder shape or does it look like a cardboard box with the top open -
If it is the latter, can you select it, then holding down the control key on your keyboard click on it to get a contextual menu, select Show Package Contents from the menu. Do you see the contents of what is actually on the Desktop here?