Bertrand Russell

Both in thought and in feeling, even though time be real, to realise the unimportance of time is the gate of wisdom.

British Philosopher

People to whom nothing has ever happened cannot understand the unimportance of events.

Understand the situation to grasp why something is described with 'unimportance'.

'Unimportance' can convey modesty when discussing personal achievements or possessions.

Sometimes 'unimportance' is used ironically to draw attention to the importance of something.

 understands both your unimaginable and fantastic importance and your complete unimportance in the larger context of the universe.