page-scroll-indicator | A very simple JS plugin to display how far a page | Plugin library

It looks like the two scripts (the one for JQuery and the one for Ripples) are not present on the home page of the site in question.

It looks like you added them to your /home page here, but that page is not set as your actual home page. You may be aware of that, but thought it was worth mentioning. Because I work with Squarespace a lot, I knew to look for that, but others here on StackOverflow would not know to go to /home to see what you're referring to. Keep that in mind.

In any case, to fix the issue, move your JavaScript code (from the first snippet in your question above) to Footer code injection instead of Header code injection. It must be in Footer code injection because, otherwise, it executes before your .ripples element is present, and so therefore the code does nothing.

So, move it to Footer code injection so that, when it runs, the element with class="ripples" is present.