Render a custom menu in a custom block
You also need to provide the actual menu config entity as default configuration in config/install. Note that test.menu.listown is not a valid menu name, they can't contain dots only alphanumeric characters and dashes.

I'd recommend to prefix all default configuration with your module name, so that they're unique. Something like mymodule-something.

And, try to follow coding standards and conventions. For example, always use camelCase for class names, like TestBlockMain in TestBlockMain.php.

And last, avoid calling render() yourself whenever possible. You can just return a render array from a block.