In languages across the world, there are words/expressions that mean both ‘Hi’ and ‘Bye’.
Ciao - Italian
Salut - French
Servus - Austrian German
Aloha - Hawai’i
Namaste - Hindi
Shalom - Hebrew
It does not matter where; which, or how old the culture is. Everyone without exception seems to have this built into their language.
I think part of the reason for this is that in every ending there lies a new beginning. Whether you see something as an end or a start reflects who you are. An optimist will look at what lies ahead and a pessimist will look backwards.
In the end, all you have is that moment in time and the attitude you bring to that present.