Moving production to localhost

I’ve migrated a whole bunch of sites from a production webserver down to my local machine running MAMP/localhost but i recently did one that created something bizarre, i’m curious if anyone can tell me what is going on.

I did these steps to create my localhost: (1) exported production database, (2) downloaded complete extract of public_html from production to local machine, (3) created my localhost directory (MAMP/htdocs/appname/public_html, (4) copied production files there, (5) created the database, imported the export from step #1, created production user in phphmyadmin, (6) stopped/started MAMP.

Now, when i try to open up the homepage via ‘localhost:8888’, instead of getting the homepage of the site, it instead downloads a file with this content:

<?php
/**
 * Front to the WordPress application. This file doesn't do anything, but loads
 * wp-blog-header.php which does and tells WordPress to load the theme.
 *
 * @package WordPress
 */

/**
 * Tells WordPress to load the WordPress theme and output it.
 *
 * @var bool
 */
define( 'WP_USE_THEMES', true );

/** Loads the WordPress Environment and Template */
require __DIR__ . '/wp-blog-header.php';

I’ve never seen this before. No errors in any logs, nothing to indicate a problem, though there obviously IS one. Can anyone shed some light on where i may have gone awry here?