Originally Posted by
Lurina
1) We can assume the third sacrifice was sapient beings even if it's not explicitly stated because the story has a broader theme of letting go of the past to secure the future, and it's stated that Hydaelyn's faction wanted the new life to inherit the star in line with the idea of 'let those who walk before lead those who walk after', so it would feel out of place if they weren't sapient.
2) The player races, collectively 'mankind', have always been meant to be Sundered Ancients.
These are mutually incompatible ideas. If 2 has been true from the start, 1 cannot be a consistent application of the theme because, again, the 'new life' didn't inherit the star. We did. And whatever the third sacrifice was has disappeared from the story.
If the theme is not being applied consistently, it cannot be used as a basis to make an inference of writer intent. We cannot use the thematic resonance of the new life succeeding the Ancients as stewards of the star to presume their sapience when they didn't.