Here is the short summary of SB 1.3 – Krsna is the source of All Incarnations:

  1. Verses 1-5: Suta Gosvāmī summarizes how the Lord expands as the three puruṣa avataras for the sake of creation. He mentions that the second puruṣa is the source of all the incarnations within the universe, 22 of which he will mention next.
  2. Verses 6-29: Suta Gosvāmī answers the fifth question by the sages – “What does the Lord do when he comes here”, by mentioning 22 incarnations and their activities. He concludes this section by saying that Sri Krsna is the ultimate source of all the incarnations and is Svayam Bhagavan (1.3.28).
  3. Verses 30-39: Suta Gosvāmī clarifies that the living entity has a transcendental form beyond gross and subtle forms. One can understand this only by pure devotional service, which is when one can also understand that the Lord’s form, birth and activities are always transcendental though he appears in this world.
  4. Verses 40-44: Suta Gosvāmī answers sixth question by the sages – “Where to find religion after Krsna departed this world”, by mentioning that in this dark age of Kali, one can find light in Srimad Bhagavatam, which is as brilliant as the Sun. He shall speak this Bhagavatam as he heard from Śukadeva Gosvāmī and as he realized it.