Wind waker is a serious headcannon right now. (Spoiler alert sort of)
Why is the former earth sage Laruto, a Zora who lives in water? And following that, Why is Medli, a bird, the replacement? It’s been a while since I’ve played Ocarina of Time, but didn’t it have Ruto as the water sage?
Firstly, I apologize for taking ages to reply, but let’s get down to business /rolls up sleeves
In Ocarina of Time, Princess Ruto was indeed the Water Sage. Laruto was the Sage of Earth, being part of the two new sages introduced to the group in Wind Waker. Hers and Fado’s duty was to keep the Master Sword capable of defeating evil, thus why you have to awaken it with the help of Medli and Makar, their descendants. Ruto and Laruto most likely were not related, and were probably from different eras (Ocarina of Time, and The Era Without a Hero/pre-flood, respectively).
Eiji Aonuma confirmed that the Rito, the birds such as Medli and Komali, evolved from the Zora, so that explains why a bird was the successor of a fish
We created the Rito as the evolved form of the Zora that appeared in "Ocarina of Time" and the Korogs as what the Kokiri became once they left the forest. They appear different, but they have inherited their blood. (x)