Display entire post navigation in single.php

I am trying to figure out how to display my entire post navigation in my single.php page but it isn’t working.

Here is a sample post on my single.php file that it currently online.
sample post using my current single.php

I have my post navigation page Here.

The problem is that In my current single.php file, it displays the navigation for the current post, but not all all the post thumbnails. I want it to display all the post thumbnails as navigation underneath the single post. Basically as if I could use like a include(‘index.php’), but that wouldn’t work.

I tried using the_post_navigation(); but it only shows the next post before and after.

Here is my single.php code below

<div id="primary" class="content-area">
		<main id="main" class="site-main" role="main">

		<?php while ( have_posts() ) : the_post(); ?>
<?php the_content() ?>
<div class="entirepost-navigation">

				<a href="<?php echo get_permalink(); ?>">
				<div class="mainpost">
					<div class="mainpostimage" style="background-image:url('<?php echo wp_get_attachment_url(get_post_thumbnail_id()) ?>')"></div>
					<h1><?php the_title(); ?></h1></div>
			</a>

</div>
	 <?php endwhile; ?>

<!-- below is the wordpress code to display the post navigation but it only displays the next post before and after but I want it to display all the posts -->
		 <?php the_post_navigation(); ?>