problem with excerptsin a default page

I want a page that displays the posts of only two categories.
I have copied the index.php, added some code of page.php before and added `<?php query_posts(‘cat=19,53&posts_per_page=5’); ?>
`. I have uploaded the file and choosen it as template for the page “Libri e Dvd”.
It works, but it displays the whole content, without cutting the text after the <!-- more --> tag. To understand, make a comparison between the https://www.dicorinto.it/index.php and https://www.dicorinto.it/libri_e_dvd/

If I change the_content with the_excerpt it displays only the text before the<!-- more --> tag, but not the image of the cover.

Can you help me understand why?

Thank you very much ??