Hey, I have issues using functions ans executes

hi, i'm creating a small datapack which has for objective:
-remove a heart permanantly tu a player when he die 
-with a special craft, he can recover his lost hearts 
Unfortunately, even though i use @s in every execute command, when à player die, every players lose a heart, and when the special item is crafted, every players recover a heart. I've tried many things, asked to coopilot, but nothing works, so i hope someone can help me !
here is a github with the datapack : https://github.com/Gabypic/health-crafter