Races of the Source vs the First and those unique to each

[ObsidianFire]

I think too much of the 1st Shard has been destroyed to say if the races we don't see on the 1st Shard weren't actually there at some point in time. Other then races like the Ixal (which are Allagan creations) it's entirely possible they migrated to different parts of the 1st Shard and were simply swallowed up by the Flood.

We've already seen that Roegayden and Au Ra are in the location of Corethas (instead of Elezen), while the Kobald and Lalafel swapped places. There's also primarily Viera in the place the Black Shroud is instead of Elezen. And the Elezen were in the 1st Shard's verions of Mor Dhona. So there's already a precedent for different races settling in different locations on the 1st Shard compared to the Source.

[Brightamethyst]

I think too much of the 1st Shard has been destroyed to say if the races we don't see on the 1st Shard weren't actually there at some point in time. Other then races like the Ixal (which are Allagan creations) it's entirely possible they migrated to different parts of the 1st Shard and were simply swallowed up by the Flood.

Pretty much this. We only know what we see. There could very well be First versions of goblins, ananta, vanu vanu, etc, and we just don't know about it because they were all gone long before we ever got there.