title, content, feature images

your code in some minor error. you can not write ‘the_content’ like this.
this is a function. your are missing brackets.

your code:

<?php the_title; ?>
<?php the_content; ?>

Replace with this:

<?php the_content(); ?>
<?php the_title(); ?>

AND for image ‘the_post_thumbnail()’ remove argument array. and check it For more detail: https://developer.wordpress.org/reference/functions/the_post_thumbnail/