Yes, if you want to ride hard and long, you're going to experience pain, I don't care what kind of bike you ride. It's going to hurt eventually. How long it's going to take before it starts hurting is not, IME, a function of age, but rather of fitness. I don't mean just fitness right now, but lifetime fitness. If you have let yourself go, far enough, and long enough, you're not going to be able to get it back. There will be too much damage. Wasting can be fixed, permanent damage can't. So there's that.

At 73, I have one minor gym injury. Most of the time, I don't notice it. No big deal. Other than that, if I'm fit for the activity, I have no pain other than that my legs hurt if I go hard enough, long enough, then my back, then my shoulders, then my butt. But everyone's do that, even the best pros. Some races, it's the guy who knows best how to suffer who wins. 250 miles with 15,000' of climbing, ridden hard, is going to hurt. So don't let anyone tell you that with x and such, there's no pain.

Sure, a century, even a double century, if easy enough and ridden at a moderate pace, say 16 average, shouldn't necessarily hurt if you're fit for it. I've averaged 20 on a flattish double in my late 50's, no pain. So that's your measure. Get fit, bye-bye pain. Train hard, train smart, train consistently, year 'round.

Your hands should never go numb. Never is a combination of experience and bike fit.

Shoulder and arm pain is just fitness. Easy peasy fix. Try working out.

Neck hurting is some fitness, some not using the proper riding position. Riding Position Discovery

Butt pain is some saddle, some position, some bike fit, some just needing more saddle time. Even after the century mark passes, I usually don't notice that I'm sitting on a saddle.

It's not good fortune. It's decades of training, study, experience, and riding. Pick it up to 5000 miles/year and watch your problems disappear. People want to attribute decades of painstaking, continuous hard work by an athlete to "good fortune." Fries my butt.