But we don't see the same species of seals or birds everywhere. There are different species which evolved to survive on each continent. Whereas humans are a single worldwide species.

Birds migrate from one place to the other they don’t live on every continent all year round. Even if we take these though (and as the other commenter said they aren’t the same species in every continent) that still leaves a total of 3 out of how many thousands, millions, of multicellular organisms on the planet.