How does your folder structure look like?
Where’s your index.html? Is your root directory set directly?
Have you got build or output folder, does it exist and was it generated?
Are you pulling this from GitHub or how do you deploy or manually uploaded via Dashboard?
May I ask could you cross-check if your structure folder is as example from below or something similar, or different?
Depending on your project, However, for Cloudflare Pages, ideally would be like I know to keep and make things simple:
main folder → named website
index.html → the main file which contains all the stuff needed (text, linked resources, etc.)
CSS directory → for any 3rd-party CSS stylings
JS directory → for any scripts I have
images directory → I put my images and icons here
After that structure, I make a zip archive from the “main folder” and then upload my zip to the Cloudflare Dashboard → Pages via Drag & Drop from my desktop.