Objective reality exists independently of human consciousness and beliefs. In other words, if people die, it will still exist. For example, radioactivity will exist no matter if people live or not.
Subjective reality exists depending on the consciousness and beliefs of the individual. It will change or disappear if the individual changes their mind or dies. For instance, the beliefs you've never shared with anyone will disappear when you die.
Intersubjective reality is a subjective reality shared by many individuals. It exists in the communication network of the group. It's more immune than subjective reality. If one individual changes their beliefs or dies, it will still exist. For instance, Christianity will still exist even if hundred, a thousand, or even a million Christians die.
Our culture is intersubjective and it has to be consciously transmitted, maintained, and nurtured. Education is an institution that does just that.
On one hand, the intersubjective nature of our reality gives us immense flexibility and the ability to innovate [2]. For example, a human child, thanks to institutions that transmit our heritage to which they have access, can in a matter of decades lead us to another planet, Mars, just as Elon Musk intends to do.
On the other hand, the fact that what makes us civilized is subjective makes us also uncommonly fragile [1]. Even a couple of decades-long break in transmission of our culture, like a global cataclysm, would probably bring us back into the middle ages.
Relevant notes (PN: )/questions (Q:):
P: Productivity is unnatural: intersubjectivity might also make us vulnerable to believing into ideas that hurt us.
Furthermore, it turns out that what is good and bad, or what is true and false, depends on the times you live in. Most of our perspectives are shaped by the collective stories of our society. These intersubjective stories change with when the external circumstances change like when new technology comes along or a natural disaster surprises us or war hit us. Morality— i.e. what's good and bad—is one of those stories and it's malleable. Don't believe it? Two hundred years ago, slavery was a regular thing, and we thought that diseases were transmitted through 'bad air.'