Finding no other similar resources online, I created this printable list of the keyboard shortcuts in Ubuntu. There’s only one change from the default shortcuts: I’ve set Ctrl+Space to be the shortcut for playing/pausing media playback. If you like you can edit the provided .odt file.

Here’s the infinitely low-tech way I got all these shortcuts as text:
After looking for a list of the shortcuts online and failing to find one, I took screenshots of them and sent them to a text identifier. Then I manually copy-pasted the output into a table.