No offense, but I would venture your food does not taste so good and a lot of what you are saying sounds like someone who is grossly inexperienced. Burning garlic and onions is the sign you are not a very good cook, for instance. That's cooking 101 and should never happen. That's like burning scrambled eggs - easy, but a sign someone is a very bad cook.

There's a very good reason chefs generally do things in certain orders, and it's not just consistency and cook time. You did not "figure out" what billions of people before you could not. A lot of the reasons why people do not cook things as you describes have to do with basic chemistry. Chemistry is what you are really neglecting given your 3 categories - things like caramelization, absorbing flavors, catalysts, reactions. Not all your choices are bad (cast iron is great), but many have consequences for flavor (coconut oil is tasty, but strong, and has a high smoke point) and others are just head scratching.

I don't even know where to start with your cooking technique, but let's discuss sautés. Firstly, you do not have to cook everything together, at the same time, same temperature, all mixed by the end. I know this sounds counter-intuitive, but some of the reasons around cook time and temperature are there precisely so things blend together well. Other reasons include removing things like water, salts, bitter tastes, etc. from food. For example, you can actually often cook your meat first to some level such as a simple browning. This will season the pan nicely, allow you to do things like sear your meat correctly, and provide some tasty fat to add flavor to your veggies while they cook. Later, you can add back the meat to finish it off and make sure it's safely cooked to the proper temperature. Your way of cooking meat is not always wrong, but for many dishes it will often have consequences - soggy meat, veggies overdone, meat not safely cooked, lack of flavor from fat, no sear, textural issues, and so on.

Pretty much the same applies to stews. For one, many if not most stews taste infinitely better if you caramelize a lot of the veggies directly in your cooking pot, then pour your liquid base on. Never mind you seem to be making stews generally without any concept of stocks and using things like butter as thickening agents (shudder). Too much water is definitely not a good thing for stew and something that is not easy to fix. Thickening stews is somewhat of an art, but there are also many well-known ways that don't involve what you describe.

I've already written a novel, but I highly suggest you buy one of those textbooks from a cooking school (CIA for example). You may look down on professional texts, but cooking is one area where learning the academics are very important. While there's always room for tweaking and personal touches in cooking, completely ignoring cooking techniques will get you no where. I am sure your food makes you happy, but if you want to challenge yourself and grow, you should really do as I have suggested and buy some books. I do not mean to harshly criticize you, but rather you seem someone interested in cooking that could maybe enjoy it more but lacks some basic knowledge to be a better cook.