Why does a chemical change change the chemical makeup of matter

Chemical change is a process where a current substance changes or is made into a new type of substance. Unlike the physical change, which is reversible. Chemical change stays into a its new form. Take for instance these -physical change- examples, making ice cubes. The process involves solidification or freezing where the water becomes ice or solid but when it melts back to its original or typical form with respect to temperature, it’s still water. When the paper is cut into pieces it isn’t burned or exposed to a stimuli that can trigger immediate change in its composition. It’s still the same. On the contrary, baking a cake involves these different compositions or substances –flour, egg, yeast and etc. that is baked to a cake, a newly formed unified substance of all the included ingredients.