

You’re throwing out entire continents worth of cuisine. You’re essentially saying “do not sauté or stir fry anything.”
But here’s the sad reality: you could live your whole life eating nothing but bland, boiled food and still get lung cancer from VOCs and PM2.5 particles in the air due to the pollution of city life.
“For some reason”
You seem like a curious person. You should do some more research into cooking and why the Maillard and caramelization reactions produce such delicious food. It isn’t the carcinogenic byproducts that taste good (those tend to be quite bitter), it’s all the other complicated compounds produced from those reactions of proteins and sugars. By the way, these reactions can be achieved without burning the food at all, just not with most traditional cooking techniques.
Even still, you can get cancer from cooking without burning food at all. Heat up a bunch of oil to its smoke point and throw some water in there. In addition to creating a huge oily mess, you’ll fill the air with countless tiny droplets of oil and polycyclic aromatic hydrocarbons (PAHs) which are a known carcinogen. However, you can reduce the risks by not reheating used cooking oil, instead using only fresh oil every time.
You can also greatly reduce the risks by not heating the oil to its smoke point. It’s actually not necessary to heat oils to their smoke point in order to achieve the desirable browning flavour reactions.
As for life time of only eating bland boiled food: I would trade away a couple extra years of lifespan for avoiding that. Keep in mind that many of the most delicious soups and stews feature lots of seared, roasted, or fried ingredients anyway. Plus as I said, you can still get cancer even if you never eat or drink anything unhealthy. The air, the soil, and the water are all polluted with carcinogens. Even switching to electric cars will not help: the road, brake, and tire damage creates loads of PM2.5 particles which will destroy your lungs. This damage increases with the 4th power of vehicle mass, which means electric vehicles (that are far heavier) are actually far worse at producing this pollution!