Wordpress虽然循环不工作打印帖子

I am a beginner for wordpress and working on creating new themes for wordpress

I added a new_theme folder in wp-content/themes folder and added below the php code in the newly created index.php in new_theme folder .

<?php
if (have_posts()) :
    while (have_posts()) : the_post(); ?>
    <h2><?php the_title(); ?></h2>
    <?php the_content(); ?>
    <?php endwhile;
else :
    echo "this is not working";
endif;
?>

After i saved the above code in the index.php i activated the theme for my current local website , But whenever i run that the loop statement just executing the first post alone.

I has 3 posts totally (post titles are new_post_1 , new_post_2 , new_post_3), the theme just printing the new_post_1 and its content (every time only the first post even the no of posts increases).Which means the while loop just terminates after the first post.