Assign template to custom page type?

Your question does not seem very clear to me but I believe this is what you are trying to do.

You’ve created a custom post-type: people. You want to have a template which displays the the archive list as well as the full content of a post which is also assigned to this template. If this sounds right, I think you could continue with what you were trying before, making use of the archive-people.php template.

You’d use archive-people.php to display the archive list of posts for this custom post-type as normal. To get and display content from a specific post/page, either before or after the archive listing, you can use the post ID of the post from which you want to display the content like the below:

// This is the ID of the post from which we want to get the post_content.
$my_post_id = 12; 

// Get the content for our specific post ID.
$my_post_content = apply_filters('the_content', get_post_field('post_content', $my_post_id));

// To print or display the content
echo $my_post_content;