Ethics as the logics of survival
Survival as the target, ethics as the science of implementing this target. Of course, we must then define who, how and over what time period survival refers to in this context.
You as the last survivor? High life and behind You the deluge? No, only survive for Yourself and for a short period of time is much to few. So let's prescribe areas and stretches of time. You as the last survivor? Living it up and never mind what happens afterwards? No, surviving all by yourself and even then only for a short period of time is much too little. So let's define some areas and time periods of survival.
If I do this, it has the following consequences. Each field in the diagram can be filled out in green, grey green, grey, grey red or red, depending on whether it is very good or very bad for this area of survival over this time period.
Fill in the diagram for each possible course of action and its possible consequences and compare the results. You will immediately see what is ethical and what is unethical.
But very soon, you will find yourself wrapped up in questions like "what if...", or "if I knew more about this...". And looking back on decisions in the history of mankind: "If they had only known this then".