I pretty much agree, though I do have a few thoughts to add.

One is that if you're doing 50 pushups you're probably doing endurance training rather than strength training, unless you're talking about doing 10 sets in a day. And if you're doing them every day you're going to build strength very slowly or actually decline in strength. You need recovery time to build muscle. If that's what you're after, do however many pushups every other day. You can work on your legs in between if you want. My legs are still pretty decent from when I used to commute by bicycle in San Francisco.

Another thought is that diversifying from extensor exercises into flexor exercises isn't even as hard as you make it out to be. It doesn't even require simple equipment.

You can bicep-curl the groceries.

You can do a pullup on a doorframe, if you can find a doorframe that won't break.

You can do one-arm inclined rows with a clothesline pole in your crotch. If you don't have clotheslines in your country, use a telephone pole.

Guys in prison deadlift the bed, or each other.

Kids climb trees and hang from horizontal tree branches. You can do that too.

If you lie down on your back under the kitchen table, you can grab opposite sides of the table with your two hands and lift yourself up with your biceps that way. If this isn't enough resistance, you can do archer rows that way. Putting both hands on the same side of the table may destabilize it, depending on the table.

I have a metal-framed transom over my kitchen door that's tall enough that I can dead-hang from it.

Fences and walls are commonly high enough that you can dead-hang from your hands on them too, though they may not be ideal for a pullup.

If you have a door, even a hollow-core wooden door, you can open the door, support its distal side with a wedge of wood (or newspaper) to take the load off the hinges, and then you can safely hang from the top of the door. This will not work with an aluminum screen door or a car door, but otherwise you're good.

Unless you live in the Gobi, you can tie a rope around a telephone pole or a tree, then climb the rope.

You can pull up to a ladder rung from underneath the ladder.

Playgrounds have jungle gyms.

Finding objects strong enough to hang from is a little harder than finding a floor, but still not a category that requires exercise equipment specifically built for it.

As for aerobics, for me the best aerobic exercise is dance, because running is boring and I don't care for the social dynamics of team sports, and running shoes are generally not helpful for dance. Many forms of dance are done barefoot; others usually use flat-soled shoes with no cushioning, on purpose, because cushioning dramatically impairs your balance. (I agree that cushioning is very important not just for running on concrete but even for extended walking on it.)

(Actually, swimming is even better, but I live too far from the river.)

Many, perhaps most, people in rich countries are experiencing levels of physical disability due to muscular atrophy that could be corrected by exercise averaging on the order of one minute per day. It's true that, to get body-builder levels of muscular development, you have to treat it as not just a full-time job but also a weird cult that fanatically controls your diet. In between the literally crippling levels of sedentarism so many people suffer, and eating kilograms of meat three times a day except when you're cutting, there is an enormous spectrum.