A ritual is any practice or pattern of behaviour regularly performed in a set manner. Anniversaries, New Year, ceremonies, weddings, holidays. The list is long and we all know that there are codified habits related with each of them.
I suppose it depends on the fact that human beings are sociable animals, so they need to identify themselves with their group, even though they might be conditioned by hierarchic positions. The common ritual celebrations mark their belonging to the group as well.
Nearly all animals have the instinct to live in a group, or in a pack, if you prefer. The ones who prefer loneliness or just a couple life are a minority.
I can think only of the majority of felines, which are solitary, and some kinds of birds.
Practising the rituals of one's own social group is a sort of language, it's somehow reassuring.
Fashion might be considered like a group ritual too, to identify oneself with the member of one's kind. People choose to wear in a similar way to affirm their belonging to a specific group.
The alternative is a kind of nearly unnatural isolation, which can be painful when it's not voluntary, but has its positive sides when it's a consequence of a free choice.
Today it was sunny and bright where I live, quite calm. Unfortunately not too winter-like.
It was a common day, exactly like yesterday.
We went out early this morning and we saw an ermine running along the road in a field. It was so evidently visible, all white in its winter fur against the field, incongruously covered with still green grass. Its fur, made to camouflage it in winter, was totally inadequate for the lack of snow.
Just another common day, exactly like yesterday.