Keynote keyboard shortcut to navigate between objects on a slide
You can navigate between text boxes on keynote without using your mouse and only keyboard by using the tab key. This has its limitation as it does not let you edit existing text but instead replace the text with what you begin texting. The process is as follows:


New Slide
Press Tab (bounding box highlights for the text box)
Start Typing (finish text)
Press Escape
Press Tab (continuing pressing to cycle)