A poster released by the College of Humanities at the University of Utah in 2015 (linked below) said that science could tell you how to clone a Tyrannosaurus rex, while the humanities could tell you why this might be a bad idea. This frames the humanities as a corrective to the possible hubris of scientists, but it also understates the case for the humanities, which teach far more than common sense.
The humanities connect cultures across time and space, increasing human understanding and cooperation and reducing small-minded xenophobia. As Oscar Wilde pointed out, an Englishman who knows and loves the literature, art, music, and culture of France is unlikely to hate the French. Someone who is educated in the humanities has access to the things and ideas that billions of people, over thousands of years, have thought beautiful, profound, or important. This broadens and deepens the mind, as well as giving the student of humanities an intellectual hinterland of human achievement on which to draw.
The breadth of intellect encouraged by the humanities is a complement to scientific study, as well as a corrective to hubris. It can also give the student confidence, pride, and a sense of possibility. The natural world, from ocean to desert to mountain to jungle, is always beautiful. It is easy (and has become increasingly common) to see mankind as a blight on this world. The humanities, by acquainting the student with the grandeur of human achievement, from Baroque dome to Shakespeare sonnet to Bach cantata to Titian painting, corrects this one-eyed view.