Setting up "amp-jekyll" plugin leads to an error

Hello, I think that I integrate in a bad way the “amp.html” file according to the documentation (https://github.com/juusaw/amp-jekyll).

I put it in the _layouts folder but without using it somewhere else. As the images I test are in _includes/header.html file which is the following:

I can’t see the utility of the “amp.html” file. Shall I change it, integrate it somewhere, reference it somewhere ? Thank you for your answer