According to some schools of thought, including most Hindu philosophies, the world is but an illusion.
Further, and more specifically to Hinduism, each person in this world encounters it or perceives it differently because of variances in accumulated karma from person to person.
Moreover, some philosophies teach that every miniscule detail of one’s life is a result of his or her sanchita (accumulated) karma.
Having said this, now picture a waiting room, at a clinic, let’s say. Maybe dozens of people come through and sit in that waiting room every day. Imagine a chair in that waiting room. Many people sit on that chair every day. To all of these people, this chair is a result of their sanchita karma. They may all experience that chair differently, or have varying memories of what the chair looked like. But it was the same chair.
A combination…a veritable stew of the karma of each of those people created the illusion that is that chair.
Something to think about when you start to think you are an island unto yourself.