What is the most important information the reader learns about Achilles from this part of his backstory?

how Achilles was trained to be a warrior
that Achilles trained with an older boy
why Achilles learned to play the lyre
when Achilles spent time in Thessaly

The most important information the reader learns about Achilles from this part of his backstory is that he was trained to be a warrior and he trained with an older boy.