Bringing all the workers of the world to unify under a single banner is possible, or not -- is some another point of discussion.
Your previous reply sounds like -- there's kinda competition going-on between societies to become more advanced, progressive, and politically stable than others by doing social services. But, now you agree that we should help everyone on Earth.
There has been a competition among nations, yes. This may have become more intensified during the rise of industrialism, which led to larger cities (and all of the social ills which came about as a result). National leaders needed more industrial workers and bigger armies to prevail in the competition among nations. Those nations which demonstrated a greater degree of kindness and generosity towards the lower classes engendered greater loyalty from the populace, leading to a more successful, stable, and prosperous society. Societies where the people were treated unjustly or unfairly led to greater resentment, dissension, sociopolitical instability, and upheaval.
However, it was also punctuated by a rise in nationalistic sentiment in that liberalism and progressivism began and ended at home. The basic idea was "we'll help our own people, but screw everybody else who is not one of us." This mentality would ultimately lead to the First World War, where one could observe multiple countries where the collective whole of the people were geared up for war, from people working feverishly in factories to build weapons and equipment, to millions of young men joining the military to go off to war - where they will kill or be killed by other young men from other countries doing the exact same thing.
It was at this point that some people began to hit upon the idea of just how absurdly ridiculous it all was, with millions of ordinary people being compelled to fight and kill millions of other ordinary people from another country. Some people thought that the world would be better off if all these millions of people stopped fighting each other and instead turned the guns on their own leaders, so that the malicious and malignant classes would be overthrown and a new, enlightened, global society could be formed, based on socioeconomic equity and human rights. Others saw such thinking as too idealistic and naive, and to be sure, global politics did go somewhat awry in the intervening years. Among other things, it led to even more intensified and atrocious form of nationalism and a war that killed anywhere between 50 to 100 million people.
My question still stands: why you want to do social service ?
Because I believe it might lead to a better outcome than world war.