Is a file hosted on a webserver discoverable/accessable if there is no link to that file in any page?

Say I have folderX on the Public_html folder of my web-server.

A) If I rename the folderX to something very long and random, is it technically possible for someone to access the files in that folder? (other than brute forcing the folder name, which should be slim chances).

B) since there is no link to the files in the renamed folder, or the folder itself, the web crawlers and search engines won't be able to index its content, right?

I understand that this is not a normal way to secure content, and it is recommend to move non-public data to the web-server root ( above the public_html) folder, or password protect them with .htaccess or so. But here I am asking what are chances, and if it is technically possible, and how?