This was intended to be a beginner challenge accessible to anyone even without any crypto experience.
tdlr;- there are lots of things that we can notice about the ciphertext- the first word has an apostrophe, we can probably guess that it says "You're" or "You've"- trying to find a pattern (and taking hints from the title), we can see that each character is shifted by its index in the ciphertext (excluding punctuation and spaces)- some manual work can be avoided by considering only the part of the ciphertext that looks like the flag
[DUCTF GitHub](https://github.com/DownUnderCTF/Challenges_2020_public/tree/master/crypto/rot-i)
[writeup](https://jsur.in/posts/2020-09-20-downunderctf-2020-writeups#rot-i)