There is a site folder which contains the template files, but assets are outside this, and content is also.
I don’t use the default folder setup. Just to see what you can do, look at this: Alternative Folder Setup.
With the various CMS, static and flat-file options out there, and considering this is a paid one
I thought the same thing a few times before I got used to the idea. You can use it without paying for it until you are satisfied. When you are satisfied with, it I don’t think it’s too expensive.
why try to re-invent wheels that went along fine?
If all of them would work the same, we would only need one CMS. About the blueprint, it’s not the only CMS that use that name and I think it’s good to not reinvent the wheel in that case. 
If you like Drupal very much, maybe you should go with that but if you want to try out something else, maybe Kirby is for you.