What are the actual roles of aged people in Asia,Africa and America?
This is such a broad question -- covering millions of people on three continents -- that a definitive answer isn't possible in this short space.
First we need to define what you mean by "aged people." How old must a person be to be considered "aged"?
If we consider "aged" to be over 65, we still have a huge variety of roles that they play in these three continents. I, along with many of my friends, are over 65, and many hold paying part time jobs, and volunteer for worthwhile causes. A large number of grandparents are raising their grandchildren.
The conventional wisdom says that the U.S. treats senior citizens as throw-aways -- but I think that has changed. American "aged" people live productive and independent lives and contribute to their communities. When they can't care for themselves, many are helped by family members while others live in assisted living or nursing homes.
Asian and African "aged" people have a variety of roles, depending upon their economic and family status. Most are also productive, although some may be taken care of by their families. Nursing homes and assisted living facilities aren't as prevalent in these regions.