How to pick up images within a post in "the loop" (wordpress)?

Question

The intention would be to make cards like this from the last posts,

Catching the first image of the post this all inside a "the loop". Chunks of the codex I tried, but it didn’t work:

index php.:

?php
if ( have_posts() ) : while ( have_posts() ) : the_post();
get_template_part( 'content', get_post_format() );
?>

content.php (part):

<img src="<?php the_post_thumbnail_url(the_post()); ?>" alt="">

Answer 1

The function the_post_thumbnail_url has as its first parameter the size that will be the image, you are passing the_post().

So you can omit the size (and then "post-thumbnail" will be used), or specify some other. Also, the method already returns the tag img:

<?php the_post_thumbnail_url(); ?>