How do I make sure a plugin loads a script after jQuery

Using wp_enqueue_script or wp_print_script function you can load your JS file after jQuery loaded. Usage Reference –

<?php wp_enqueue_script( $handle, $src, $deps, $ver, $in_footer ); ?>

The $dep argument (dependencies) should be an array or null or empty, and should not be used the way you did on your code. It will be on with wp_enqueue_script or wp_print_script function.

Your first used add_action reference is valid, but the second one is invalid.

On your stb_enqueue_scripts function, it should be –

function stb_enqueue_scripts()
{
    // third argument is the dependencies, should be array or boolean false
    // fifth argument = boolean true if loading the script at footer
    wp_enqueue_script( 'script-name', 'script_url', array('jquery'), '', true );
}