I have posted before on why exercise is so helpful. This is just a quick list of the benefits:
The exercises you listed are certainly helpful to overall well-being. Keeping a strong core with those types of exercises is great for maintaining skeletal and muscular strength.
But do you know the most important muscle to exercise? Your heart, of course. Exercising your heart will also benefit your entire cardiovascular system (capillary density & mitochondria) and your lungs, as well as your heart.
And whenever you exercise your heart there is some area of muscles that is also getting a workout - arms, legs, or both.
The list of things you described are beneficial but are not enough to give your heart a sufficient workout. You need to maintain a higher heart rate for a period of time for your heart and cardio system to get enough benefit.
So there needs to be something you can do that gets your heart rate up consistently for a period of time. You can start slow with walking, or jogging. Or cycling, or a stationary bike. A rowing machine or swimming. You need to find something that you enjoy (or at least can tolerate) enough to keep you doing it consistently.
For the heart benefits there really aren’t any shortcuts. It takes a certain amount of time several times a week. It will take dedication.
We can get into specifics if you would like. Things like heart rate and duration and so forth. And you should discuss certain safety limits with the doctor you visit if you do a calcium score test.
The benefits are huge though. You can watch your insulin requirements drop and your insulin uptake speed increase, and if you are interested in weight loss that can happen too.