Why do I have to upload a table of contents(TOC) just for a short story?
It's the nature of the formatting beast. All you have to do is apply a heading to a couple of things and that will be sufficient for a ToC. Apply Heading 1 to your title and again to your Copyright and you're good to go.
Because it is a requirement if you want your book to be distributed beyond Lulu.
HJ Peterson is correct; do this and you will be good to go.