jQuery inluclude still seems ncessary for script to work within post

In order to use $ inside your script (You only need to change the wrapper of your script), use the following wrapper.

jQuery(document).ready(function($) {
    // $() will work as an alias for jQuery() inside of this function
});

Make sure you enqueue jQuery in one of your plugins or theme using wp_enqueue_script('jquery');

Read more on Codex

http://codex.wordpress.org/Function_Reference/wp_enqueue_script

The following article contains useful tips on using jQuery with WordPress.

http://www.ericmmartin.com/5-tips-for-using-jquery-with-wordpress/