"The Prologue" and "The Author to Her Book"

The Prologue
To sing of wars, of captains, and of kings,
Of cities founded, commonwealth begun,
For my mean pen are too superior things:
Or how they all, or each their dates have run
Let poets and historians set these forth,
My obscure lines shall not so dim their worth.
Why does she seem to be putting down her own ability to write? Mean, humble and thin? Why does she call these subjects of poetry "superior things"? Do you think she personally finds them "superior"? Why are they "things"? obscure" can mean: inadequately provided with light, not readily perceived, remote from centres of h…