Overall the structure of the essay is clear. There is no detrimental grammar mistake in your writing.
A few things to improve:
(1) since the dawn of human beings => this is a cliche. Best to avoid.
(2) They assume that it is a huge waste of money because most of them are poor and art is something luxurious. Such poverty not only prevents them from enjoying music, poems or pictures but also leads them to emotionlessness as a result of being eroded by drudgeries and stressful objectives => This is a weak & unclear argument. It sounds a bit offensive and patronizing as well.
(3) Some can even make music and draw pictures with the most rudimentary rocks or stones => Evidence? Too big of an overstatement I think.
(4) they can bestow us => inappropriate use of this word here.
I fixed your essay below. Hope it helps. Keep up with the good effort.
Art, music and literature have been essential parts of our life. While some investments in these fields meet little success, I would argue that governments should continue to support artist, musicians and poets financially.
Some people stand against this policy for several reasons. To them, art is representative of eliticism and priviledges enjoyed by the wealthy. Additionally, the more money governments spend on art, the less funding they have to develop other key industries and solve urgent problems. For example, housing crisis, migrant crisis or social welfare should receive more attention from governments.
On the other hand, providing financial support to artists, musicians and poets is beneficial to the society in general. In fact, regardless of their socioeconomics background, people would find a way to enjoy music or poems. Governments, when they invest in the right people at the right time, might not only nurture the cultural lives of civilians but also bring out many talents for the future. In addition, there are hidden aspects of art and music that can be exploited to enhance tourism. No sooner are artists, musicians and poets backed with financial support and facilities than they can come up with new ideas, from traditional to modern works, that would attract a greater inflow of tourists, thereby improving national economy.
In conclusion, supporting artists, musicians and poets comes at a price that not everybody would be willing to pay. However, with a sensible level of public investment, they would generate both economic and cultural values to society.