Your webserver configuration doesn't seem correct. If using Apache, make sure Flarum's htaccess is correctly loaded. For nginx, make sure your configuration is based on the example from the docs.
If you moved the public folder, make sure you followed the special instructions in the documentation ("custom paths")
And finally your forum is accessible from multiple origins, which can cause its own errors (the CORS issue). Check that the url value in config.php matches your expected host and add a redirect in the webserver configuration so that your forum can only be load via the www subdomain or the apex domain.
