Is there a keyboard shortcut to navigate one level up in Finder?
The one you're probably looking for is the command ⬆︎ keyboard shortcut, as this is the one that takes you back to the parent folder. 

To do the same thing, but within a new window, use command control ⬆︎.

However, some views offer additional options. For example, in Columns view you can just use the ⬅︎ key to go back to the parent folder.

In addition, you can use the command [ keyboard shortcut to take you back to the previous folder you were actually in (which may not necessarily be the parent folder).

You can also right-click on the title in the Finder's window to select anywhere in the file's path to go straight to that location.

Finally, you can also customise the Toolbar to add the Path button.