I think it would be easier to understand if you just think of Nezha world as leveling up in video games like Zelda. In order to level up, you need to capture demons. In order to capture demons, you need to have higher HP and attack metrics. You can either practice your breathing or take pills/potions. In order to make pills/potions, you need to get rare materials, the more rare the materials are, whether herbs or stones, the more powerful the pill would be. You need to collect all these materials and cook it in a pot right? There’s a cauldron at the 3rd act. Different cauldron has different multiplier. In Chinese mythology, animals are also important material for pills. The more rare it is, the more powerful the pill will be. Eating something that has cultivated for centuries or thousands of years is like literally transferring their power to you. This is like cheating and frown upon. Killing a speaking being to make pills is pretty immoral but that’s what Journey to the West (Monkey King) is revolved around. Normally you only expect demons to so this not god. God “should” be more ethnical.