It is not that Bird is so high on this list that is surprising, more so that there are four other cards between it an Noble Hierarch which is a very similar card and situationally better than the Birds
Locations might prevent characters from being challenged, bolster their stats, and way more besides
Sapphire continues the trend from Rise Of The Floodborn of showing how powerful synergy between characters can be with Huey, Dewy, and Louie, particularly with Huey's ability, Three Nephews, which allows you to draw three cards if one of each of the Nephews is on the field
Theres no single right choice
Normally Id focus on Commander, but it didnt feel fair to use Commander as the baseline since many of the best sorceries in Magic arent legal in Commander
Many of the cards that they chose slot well into various Limited archetypes