function redirect_non_admin_users_to_frontend() {
$current_user = wp_get_current_user();
$allowed_roles = array('administrator', 'editor', 'author', 'contributor', 'shop_manager');

if (!array_intersect($allowed_roles, $current_user->roles)) {
wp_redirect(site_url('/'));
exit;
}
}

add_action('admin_init', 'redirect_non_admin_users_to_frontend');