A few suggestions. My first is to keep what you are doing about fancying up store bought items. It's so easy to elevate a store bought sauce with some herbs, spices or a few cooked items like sausage or mushrooms. Go crazy with whatever you think will taste good. Add way more herbs and spices then a recipe suggests to see what it tastes like. From here you can spend more time to find what is "worth it" to cook "from scratch". Unless you are a professional kitchen there's always items you will make and those you buy.

Second if you want to learn the science and technique of cooking (which you might not want to) there's one cookbook you need. Salt, Fat, Acid Heat will talk about what you need in each dish. There's also a netflix series about it if you want a preview. Have fun and eat!!!!!