Image folder structure

I want to place a folder containing many images without using the extra asset folder.
In that case, I want to know what to do with the folder structure.

I want to know the benefits of using the Extra Assets folder.

The extra-assets folder is the only way to upload additional asset files to Shapespark hosting, if you use some other folder name, it won’t be uploaded.

Thank you for answering.
Is it okay to use other folder names if I don’t use shapespark hosting?
What is the role of the dir file?