I had fun playing this game. I love action games, so I immediately jumped into it because that genre is already something I enjoy.
The concept is cool, and I liked the idea of fighting beginner monsters that turn into souls and can become stronger if you hesitate too long. That gives the game a nice sense of pressure.
My main feedback is that I wish there were clearer feedback when fighting the ghosts. Sometimes I was not sure if I was actually dealing damage or if my attacks were connecting. A stronger hit effect, sound effect, health bar, flash, or knockback could help make combat feel more satisfying.
I also think it would be cool to have another attack or ability to change things up during fights. Even one extra move could make the combat feel more dynamic.
Overall, I enjoyed it. For a first Unity game and first jam entry, this is a strong start. I would love to see where the game goes if you continue working on it in the future.