It's the same old edition problem. Each edition tries to "fit" each race or creature into the "new rules". But, a lot of it is just someone somewhere just says "they are X", for this edition.
All three were just normal mortal beings in Ye Old 2E Spelljammer....though each did have a "special" bit about them so they were not 100% normal beings.
3E started it by making the Mercane suddenly outsiders. Reigar too. Though 3E also kept the humanoid Mercane too. And space whales were just creatures.
By the time you get to 5E, most creatures have jumped all around as to "what" they are "now". Technically even in 5E Mercane should be "outsiders" or "planuals" or such as a neutral non mortal plane hopping race. But 5E does not go into such detail for planual races. Maybe the Planescape Product will fix it?
Space Whales are "celestials" as they need to be non-mortal plane travelers....as 5E Spelljamming is Planejamming. So Kindori fly up into 'space' of the 'Astal Sea' and 'swim' around the Multiverse in 5E.
If they change around all the types of creatures again for "not 6E" they will likely change everything again.
All three were just normal mortal beings in Ye Old 2E Spelljammer....though each did have a "special" bit about them so they were not 100% normal beings.
3E started it by making the Mercane suddenly outsiders. Reigar too. Though 3E also kept the humanoid Mercane too. And space whales were just creatures.
By the time you get to 5E, most creatures have jumped all around as to "what" they are "now". Technically even in 5E Mercane should be "outsiders" or "planuals" or such as a neutral non mortal plane hopping race. But 5E does not go into such detail for planual races. Maybe the Planescape Product will fix it?
Space Whales are "celestials" as they need to be non-mortal plane travelers....as 5E Spelljamming is Planejamming. So Kindori fly up into 'space' of the 'Astal Sea' and 'swim' around the Multiverse in 5E.
If they change around all the types of creatures again for "not 6E" they will likely change everything again.