We live simultaneously in time and eternity although usually we notice only the passage of time. The intersection point is the present. We are always in the present although everything is always changing.
The dead are only in the past because they are not alive. However, everyone is alive at some times and dead at others. Most potential people are not born but can be represented by fictitious characters. Birth as a human being is a rare opportunity. We cannot choose who we are born as - life is born as everyone - but we can do something with life while we have it.
These statements are tautologies which are the most basic kind of truth.