WordPress shortcode php issue

I would like to add blog feed into my WordPress static page(Show last 3 posts in a div). Since wordpress doesn’t execute php code inside posts/pages, I want to do it using shortcode.

I have created feed.php file which contains

<?php

function getblogposts() {

wp_get_archives( array( 'type' => 'postbypost', 'limit' => 3, 'format' => 'html' ) );

}
?>

And added code blow to functions.php: (using child theme)

<?php
include(WP_CONTENT_DIR . '/feed.php';
add_shortcode( 'getblog', 'getblogposts' );
?>

And unfortunately, when I input [getblog] into the site, it displays as raw [getblog].

Any idea what I’m doing wrong?