Hi @petprintpaw 
It’s not possible to rename files after uploading. The original file name will be preserved and stored in file metadata. However, you can use any file name after the last slash in CDN URL. For example, these URLs are referring to the same file
https://ucarecdn.com/d5049d10-0ba5-4c2f-8ebc-43975d37c933/droppedkitty.jpg
https://ucarecdn.com/d5049d10-0ba5-4c2f-8ebc-43975d37c933/cat.jpg
https://ucarecdn.com/d5049d10-0ba5-4c2f-8ebc-43975d37c933/image.jpg
Hope that helps.