Deserving has nothing to do whether one is self-centered. And even if it is "nothing to brag about" the fact remains that the writer is boastful.
Wow, how anyone could see David's marveling that God even notices him as self centered is beyond me.
Lord, our Lord,
how majestic is your name in all the earth!
You have set your glory
in the heavens.
2 Through the praise of children and infants
you have established a stronghold against your enemies,
to silence the foe and the avenger.
3 When I consider your heavens,
the work of your fingers,
the moon and the stars,
which you have set in place,
4 what is mankind that you are mindful of them,
human beings that you care for them?
5 You have made them a little lower than the angels
and crowned them with glory and honor.
6 You made them rulers over the works of your hands;
you put everything under their feet:
7 all flocks and herds,
and the animals of the wild,
8 the birds in the sky,
and the fish in the sea,
all that swim the paths of the seas.
9 Lord, our Lord,
how majestic is your name in all the earth!
Who is David centered on here? Not himself!