Why WP_Query(‘showposts=5’) shows only 1 post?

the_content_limit does not exist in WordPress. You probably want something like the_excerpt.

What’s likely happening is your loop is working fine, but the call to an undefined function causes the program to error out, making it appear the the loop is not working. Look at the rendered HTML: you’ll probably see a single, opening <li> tag, the link and an opening paragraph tag.

showposts is also deprecated. Take a look in the codex: dropped in 2.1

Try this:

<?php
$query = new WP_Query(array(
    'posts_per_page'   => 5,
));

while ($query->have_posts()): $query->the_post(); ?>
    <li>
        <a href="https://wordpress.stackexchange.com/questions/85256/<?php the_permalink(); ?>"><?php the_title(); ?></a>
        <p><?php the_excerpt(); ?></p>
    </li>
<?php endwhile;