Glory of lord Rama speaks why he took the form of a human being on being an absolute or unqualified Brahma. Though it is clear as any thing that he assumes form on for the welfare of his devotees but still virtues names stories and forms of lord are all unlimited, innumerable and immeasurable.
The cause of his descent can not be precisely stated as lord is beyond the grasp of intellect, mind or speech: such is conviction of saints on for life.
Saints, seers, sages and intellects have given their version with laud on the glory of lord with cause of his assuming different form and all have same essence their in that whenever virtues declines and vile and haughty demons multiply and work uniquity that can not be told, when ever Brahmans, cows, gods and earth itself are in trouble, the gracious lord assumes various transcendent forms and relief the distress of the virtuous.
Killing the demon acts and reinstates the fairness to life on the verge of truth in all respect, preserve the bounds of propriety fixed by the ancient books and the Vedas, which represents his own breath is one of the motive of his descent.
May lord bless all on the subject of true human life.
Thanks please.