By default, if you choose a static Page for Posts page to show your latest Posts, the original content of that Page will not be displayed.
This is how you can display the content of the Page along with the latest Posts.
Add the following lines to your WordPress Theme’s template index.php file, preferably before the loop:
<?php
if ( 'page' == get_option('show_on_front') && get_option('page_for_posts') && is_home() ) : the_post();
$page_for_posts_id = get_option('page_for_posts');
setup_postdata(get_page($page_for_posts_id));
?>
<div id="post-<?php the_ID(); ?>" class="page">
<div class="entry-content">
<?php the_content(); ?>
<?php edit_post_link('Edit', '', '', $page_for_posts_id); ?>
</div>
</div>
<?php
rewind_posts();
endif;
?>