To display the category image for the currently displayed category in archive-product.php, use the current category term_id when is_product_category() is true:
// verify that this is a product category page
if ( is_product_category() ){
global $wp_query;
// get the query object
$cat = $wp_query->get_queried_object();
// get the thumbnail id using the queried category term_id
$thumbnail_id = get_term_meta( $cat->term_id, 'thumbnail_id', true );
// get the image URL
$image = wp_get_attachment_url( $thumbnail_id );
// print the IMG HTML
echo "<img src='{$image}' alt='' width='762' height='365' />";
}