My first track and "hard rejected', what's wrong? help,please

Hi everyone. I see here many rejected tracks with your opinions and advice. I ask for help to understand why my first track was hard rejected. I’ll be grateful for any advice, thank you!

Well , I can say that the mixing was awful and the balance between the tools you need to build !!!
to change one chord in harmony , and make not such a abrupt ending !!!

Personally, I think it’s a good idea but needs developed a little bit. The piano would benefit from a little more dynamics, it sounds like all the notes are at the same velocity. The acoustic guitar sounds like it gets a little out of tune or something around 0:20, but the main thing the track seems to want to build up to something but it kind of just stops without getting to that point. Hope that helps!