Thank you so much for your feedback!
The life system is actually added to hide a bug. During the development period, we noticed that if the player keeps on dying and restarting, the game can get very laggy. We couldn't find what is making it laggy. So, we decided to add a health system to cover up this bug.
We have some small white diamonds throughout the level which you can collect to increase your life count. Maybe we should add more of that.
Wow, not many people like the dimension switching mechanic, especially when they are bound up to shooting.