I would like to add my thoughts, hoping it will not offend anyone:
This extremely beautiful song is a lovely meditation of Dikshitar on Rama. It is great religious poetry.
For example, Rama is the consort of Bhumija=Sita (hinting that as Vishnu is he the consort of Bhudevi) and Sriman=consort of Sri or Lakshmi...and he gives Bhukti and Mukti (worldly enjoyment and liberation)!
He is Upendra=the younger brother of Indra (my father's translation based on Madhwa's commentary also states so) and yet is also worshipped by Indra (Nakeshanuta)!
Dhiman, Sriman = the truly intelligent are liberated! Rama is Purushottama hence Naravara and so is Bhagavan! No wonder he is extolled as the ultimate among men.
Lateral thought: in Bhgavadgita, Krishna says he is rAmo ShatrabhRtAm vara. So among those powerfully endowed with weapons, Rama is the ultimate. Why? Because he never used his power to conquer and possess. In this context I am reminded of Osho's beautiful saying. Ravana was killed by Rama. The beauty of this is that it is unusual: one conquerer is generally conquered by another, and they are indeed not different from each other, because they are all after power. But Rama was uniquely different, as he was not after anything! So Osho says that Ravana, at the moment of his death, bows down to Rama and says that it is in the fitness of things that truly Right has won over Might.
Rama gave the ultimate Samrajya to Hanuman=Ramabhakti!
He is infinite=Anantha yet also human=Nara!
He dwells within Guruguha and hence is worshipped by Dikshitar through his Ishtadevatha.
The alliterations and rhymes, the contrasts and comparisons, all are as beautiful as the melody in the Vasantha song.
And Rama was born in the spring time or Vasantha (most of India has spring bloom at the time of Feb-April, with lovely yellow and marigold and red flowers), although technically its on the ninth day of the new year or Chaitra.