The main audience for the site is people who already have some facility in playing a keyboard instrument (in any genre), and who want to learn jazz or improve their jazz playing. It assumes a basic understanding of how scales and chords work.
Building the animated keyboard that accompanies each musical example was quite a rewarding technical challenge. For anyone interested in the details, there is a blog post about it at https://www.jamieonkeys.dev/posts/piano-keyboard-javascript/.
I hope folk find the site to be a helpful resource. Feedback and bug reports welcome!