All I see in the html section is:
The head element is not were you put html elements you want to be visible on the page. Those will go in the body element. You put other things like the title tag and meta tags in the head element, but in Codepen that is handled differently. Other than the head element, you want to put your html elements in the HTML section which Codepen automatically puts in the body element (behind-the-scenes) for you.
Below is the general template for a page.
<!-- things like the title tag, style tag and meta tags go here and in Codepen you use the HTML settings section to add these -->
<!-- this is where all your visible content needs to go and in Codpen the HTML sections represents what will be in this section -->
<!-- at the bottom is typically where you want to put your script tags, but in Codepen, you add them using the JS Module as external links-->