Jquery was not found on this server

The proper way to include jquery in your plugin is

/**
 * Proper way to enqueue scripts and styles
 */
function theme_name_scripts() {
    wp_enqueue_script( 'script-name', get_template_directory_uri() . '/js/example.js', array(), '1.0.0', true );
}

add_action( 'wp_enqueue_scripts', 'theme_name_scripts' );