There are many reasons that art is important - but two stand out as primary. The first is that art is one of the only four ways in which a human being can have an unmediated experience with those essential things that are beyond description in words. These things include love and faith and hope, which are among the most critical and meaningful aspects of the human experience, but are totally incapable of being fully expressed in words.
Yet we can access our sense of them when we are with nature, or in prayer and meditation, when we listen to music - or when we view art. In these four places, we can drop into our most soulful states and open into a state of communion. An artistic image - and possibly the original intention of the artist which we sense - can assist us. Our brains are designed for symbolic shorthand, and art is full of it.
Joseph Campbell, philosopher now passed and an American Buddhist, once said that when we view an artwork that is meaningful to us, it has the potential to give us the same thing that Buddhists strive for, which is satori. Campbell described this as a moment when the brain’s chatter stops, just for an instant - a very precious instant.
The second primary reason that art is important is that it is our most significant record of all human society. Almost everything we know of history outside of things that are in the nature of granary receipts, comes from art. It tells us how societies thought, associated, moved, ate, lived and died. From this we learn the rich tapestry of not only our past, but the past of other cultures. We share ideas. We discover what worked - and what did not. We have the opportunity to learn, to broaden ourselves in the present, and - at least theoretically - to avoid mistakes.
Most importantly, we become part of a family, so that we are not existentially isolated blips. Art gives us a way to see ourselves in a greater context. Socially, psychologically and in all ways for humans - invaluable.