We went to the grocery store the other day and came to a 4-way stop.
The car on the right got there first, then the one in front, then we did and finally the one on the left.
I waited our turn, drove off, pretty smooth interaction.
Those three cars were the most relevant moving objects at that moment because they were the only thing that may keep us from reaching our goal of going to the grocery store if the interaction ended in a collision.
There were dozens of other cars in the parking lot but none of them were relevant at that moment.
This 4-way stop represents some of the interactions you and I have in life, daily, with others.
We are at point A (say you’re hungry) and want to get to point B (eat and satisfy hunger).
We’ll interact with others to get to point B. Clerk at grocery store, plans with the loved ones to cook dinner, drive-thru cashier at the McDonalds. Whoever it is, they are the most relevant at that given moment.
Everyone else is irrelevant at any given moment.