Show product thumbnail on woocommerce New Order email

add_action( 'woocommerce_add_order_item_meta', 'add_random_number_item_meta', 10, 2 );

function add_random_number_item_meta( $item_id, $item_data ){
  // store each product item quantity in array
  $random = array();
  for( $i = 0; $i < $item_data['quantity']; $i++ )
  $random[$i] = rand(10000, 90000);
  // save unique numbers array each order item
  wc_add_order_item_meta( $item_id, '_unique_nos', $random );   

}

//woocommerce\emails\email-order-items.php

 $unique_numbers = wc_get_order_item_meta( $item_id,  '_unique_nos', true );
 echo implode( "," , $unique_numbers );

// This will be same both for admin or customer

add_action( 'woocommerce_email_after_order_table', 'custom_email_after_order_table', 10, 4 );
function custom_email_after_order_table( $order, $sent_to_admin, $plain_text, $email ) {

    // Displaying the shipping method used
    echo '<p><h4>'.__('Shipping', 'woocommerce').':</h4> '.$order->get_shipping_method().'</p>';

    $product_names = array();

    // Loop thougth order items
    foreach( $order->get_items() as $item_id => $item ){
        $product = $item->get_product(); // Get an instance of the WC_Product object
        $product_id = $item->get_product_id(); // Get the product ID

        // Set each product name in an array
        $product_names[] = $item->get_name(); // Get the product NAME
    }
    // Displaying the product names
    echo '<p><strong>'.__('Product names', 'woocommerce').':</strong> <br>'.implode( ', ', $product_names ).'</p>';
}

add_filter('woocommerce_email_subject_new_order', 'change_admin_email_subject', 1, 2);
function change_admin_email_subject( $subject, $order ) {
    // HERE define the product attribute taxonomy (start always with "pa_")
    $taxonomy = 'pa_color'; //

    // Loop through order items searching for the product attribute defined taxonomy
    foreach( $order->get_items() as $item ){
        // If product attribute is found
        if( $item->get_meta($taxonomy) ){
            // Custom new subject including the product attribute term name
            $subject = sprintf( '[%s] [%s] New customer order (# %s) from %s %s',
                get_term_by('slug', $item->get_meta($taxonomy), $taxonomy )->name, // Term name
                wp_specialchars_decode(get_option('blogname'), ENT_QUOTES),
                $order->get_id(),
                $order->get_billing_first_name(),
                $order->get_billing_last_name()
            );
            break; // Stop the loop
        }
    }

    return $subject;
}

add_filter( 'woocommerce_order_item_name', 'product_title_under_thumbnail_emails', 10, 3 );
function product_title_under_thumbnail_emails( $item_name, $item, $is_visible ) {
    // Targeting view order pages only
    if( is_wc_endpoint_url() )
        return $item_name;

    // Get the WC_Product object (from order item)
    $product = $item->get_product();

    if( $product->get_image_id() > 0 && $is_visible )
        $item_name = '<br>' . $item_name;

    return $item_name;
}