Thank you for the valuable feedback.
I forgot to implement a way to go back so players can collect the spirit containers you already collected and some spirit balls to fill up their lives.
I will add a mushroom so you can jump back and collect spirit balls there are more than 50 in the room some are hidden. You need 100 so it won't take much time. I will upload the update soon.
But I can't give the players full lives at every checkpoint because you can get up to 9 lives and often there are many checkpoint so that players would be able to run mindlessly through later parts of the game without ever risking to die.
What I did instead is giving players floored 50÷ of their max. lives. So if you have 9 Livecontainers and less then 4 lives you will have 4 lives after saving at the next checkpoint.