The PHP code you shared registers the block on the server side, and this information is passed to the block editor via the REST API.
However, no information about how to display or edit the block is included with this, there is no edit component, no save component, and no JS file referenced. So there is no way to show your block in the block editor with just what you’ve told it. Using this method still requires that the block be registered in javascript too
It is possible to specify a JS file when using register_block_type but you would then need to register the block in that file and pass it the necessary save and edit parameters. Not only that but the title, icon, block category, are all missing.
The easiest method is probably to use register_block_type_from_metadata and provide it the folder/path of a block.json file. This is a more modern version of what you’ve used, and it will process relative file paths to load edit and save component JS in the same folder.
This is what the WP Scripts block scaffolding will do. It also auto-generates some PHP that can be used to enqueue the needed scripts for the block automagically, and it sets up React etc and commands/docs to build and do live in browser rebuild/refresh.