It's possible that - in the grand, cosmic scheme of things - it doesn't matter.

Philosophers have been kicking that around for thousands of years. In another thousand years, they'll still be kicking it around.

People of Faith tell us that each of us matters to the mind of God as if no one else existed . . . that we are each infinitely loved.

A poet, Matthew Arnold had this commentary on that:

"The Sea of Faith
Was once, too, at the full, and round earth's shore
Lay like the folds of a bright girdle furled.
But now I only hear
Its melancholy, long, withdrawing roar,
Retreating, to the breath
Of the night-wind, down the vast edges drear
And naked shingles of the world.

Ah, love, let us be true
To one another! for the world, which seems
To lie before us like a land of dreams,
So various, so beautiful, so new,
Hath really neither joy, nor love, nor light,
Nor certitude, nor peace, nor help for pain;
And we are here as on a darkling plain
Swept with confused alarms of struggle and flight,
Where ignorant armies clash by night." From: Dover Beach

The message there, I think, is that we don't matter, except as we matter to someone. That's as good an explanation of the pain of loneliness as I've yet found. The poet tells his love that they must matter to each other, if they are to matter at all.