Our ancestors told stories; stories that entertained, that showed people how to live, and that explained how the world was ordered. They sat around campfires, and around the work they were doing at the moment and told stories and sang songs. As People became more numerous, they gathered in cities and the stories got bigger, the presentation more formal and particular. The telling moved beyond just one person and others played roles. The stories of how the world was created were acted out yearly and with precision. On flaw in the performance and the players must start again least the world not function as it should.
The priests would enter bringing with them the sounds of chanting and the smell of incense. What storytelling lost in intimacy, public performance made up for in created spectacle. The grand theatre of the temple, housing statuary, and carved with reliefs of the doings of the gods, the choice of time of day, the smell of the sacrifice, and the sound of human voices raised in praise, all enveloped the participants. It allowed them to step out of ordinary time and join in the creation of the world, the crowning of the god-king, and the sparking of the fertility by which humanity survived. And whether around the fire or in the temple grounds, such participation bonded the people to each other and invested them with meaning and purpose. Such is the definition of ritual.
Good ritual is still a performance, and an artistic production, whether that ritual is done by a solitary practitioner or a group of 300. Without the special clothing, the candles and the incense, the hypnotic music, the altars and the tools, it becomes much more difficult to alter our consciousness and enter non-ordinary reality. In order to connect with the gods, the ancestors, to feel that unity, we engage our physical senses. If the engagement is strong enough, if the performance is sufficiently convincing, our senses are overwhelmed, and for a time outside of time we can touch the unseen world.
Humans are designed so that we can change how we see the world. It is part of our brain function, and doing so in groups makes it easier because we are also built to be tribal. To join together in the theater of ritual part of being human.