Unfortunately, the level of average physical fitness in the general population seems to be decreasing continuously. If you look at the big picture we are so far from our true potential that some people (one of them being Erwan LeCorre) consider that most of us are zoo animals by choice. Our ancestors were in amazing physical shape if you think how they used to hunt with almost nothing (maybe a spear). Our ancestors were able to crawl, jump, climb, squat and run. The best example of what we used to do as a species are our own children. If you watch a 3-4 year old child doing all kind of crazy stuff it is because they have a strong instinct to practice for a life that does not exist anymore.
Nowadays I think pretty much anybody can benefit from whole body exercises. The most available options are yoga and tai-chi. There are also many online options with Diamond Dallas Page Yoga (DDPY) being one that I recommend frequently to my patients. The Arthur story is a pretty remarkable success story of the DDPY approach. For self training I usually recommend the book “The Practice Of Natural Movement” by Erwan LeCorre. If you have access to specialized professionals some other whole body approaches are functional movement and dynamic neuromuscular stabilization.
It is never too late to start exercising. The best is to create habits and be consistent. George Bernard Shaw said: “We don't stop playing because we grow old; we grow old because we stop playing.” The same is true if you replace playing with exercising.