Regarding the page's "poor UI usability" without obvious navigation buttons: I'm guessing the page is intended for the author's use in live presentations (like MS PowerPoint) and is not meant to be a general purpose landing page.
The author used it that way here: https://www.youtube.com/watch?v=9QObt0SGriI
(I haven't seen the whole presentation so I can't comment if it's worthwhile to watch.)