How can I get the default content of WordPress post?

by

Yes you can access the post_content property in the loop from the $post object

if ( have_posts() ) : while ( have_posts() ) : the_post(); 
  echo $post->post_content
endwhile; endif;

Mention that the post_content is coming straight from the database.
All ‘the_content’ filters will not be applied.

For more properties see the post codex