You dont need the query at all, the default is to show all the files on the page. Unless…do you have other file types on the page and you just want to show images in it?
If you want to restrict the type of images that can be uploaded to the page via this field, you have set the upload property with a template that contains an accept property.
With the above file field setting, I can only select images, not documents etc.
You can, however, upload other files if you don’t restrict this in the uploads option by setting a files template and
uploads:
template: files-upload
inside this template, set the accept property.
However, without this setting–and that’s probably a bug–while other files are not selectable, a file uploaded that is not an image is immediately selected without Kirby complaining.