We are just fellow traveller in a train- used as a metaphor here- and when our parents passed through a station called ‘Child’ then a child, we as their kids, enter into the bogie and be seated near them . Then train reaches a lot of stations and people get added in our life as friends from Friend station, Wife/Husband from Marriage station etc etc they all were unknown before and is going to leave us for sure as Soon as that person‘s destination station arrives. However loving and caring the person may in our life but that person is not going to care about all others. Same is the case with all others too. So take it lightly.
But for a human being watching this life as a train journey could bring miracle because it is the watcher that is eternal, infinite and constant. It was with us from childhood. It is the one which tries to discover the word or name when our mind forgets it!