Why do I get 404 errors when the file exists?

I've been coding my final project for my CS course with brackets, and it runs just fine locally. However, when I run it on a web server it returns a bunch of 404 errors. I am confused because I have double-checked the file paths that it claims "doesn't exist", and they are there, no difference in path or name. I assume it has to do with permissions, however, I am unsure. Please help with this as the due date is rapidly approaching.

I have provided the error messages, along with the file paths.

File Paths
Error Messages
Code Snippet #1
Code Snippet #2