In most countries copyright lasts for 50 years from the death of the author, or 75 years in some countries. So the works of an author who died less than 50 years ago will generally still be copyrighted.
An author can waive copyright on some or all of their work and allow it to be freely reproduced, but that is really up to them, not something for others to decide. It is the author's intellectual property, so just taking it is not all that different from borrowing their lawnmower without asking.
I was just thinking about the idea of a cashless society the other day. If we did live in a cashless society, it seems to me like the next useful evolutionary step forward for such a society would be the invention of money. For example, say you have grown plenty of pumpkins, and Pete down the road has grown a tonne of cucumbers, and he wants some of your pumpkins. Now sure you could trade pumpkins for cucumbers, but what if you dislike cucumbers, and what you really want are some strawberries from Jill round the corner? If Pete could just give you some token conventionally accepted within that society as representing value, but of no intrinsic material worth, then you could take that token round to Jill, who may have an aversion to both pumpkins and cucumbers, but be wanting some of Jackie's free-range eggs, and give Jill some of the token currency so you can get some strawberries, and she can get some eggs.
The alternative would be that everything is free and shared, but I think there must be a limit on the population size within which that would work. It is normal to share for free within a family unit, but in larger groupings like a village, or a city, I think it would become exponentially more difficult to just have everything available free.