Humans are everywhere!

[Munchlax]

Has there been a plane without humans yet?

[Remillo]

Lorwyn, though Changelings are /technically/ human.

[The1337Magician]

Lorwyn, though Changelings are /technically/ human.

Technically:
{Chandra Nalaar}
{Garruk Wildspeaker}
{Jace Beleren}
& {Liliana Vess}
But they're not native.

[Remillo]

Rath, except for Yawgmoth

The Vec and the Dal were humans on Rath, though the Kor were a different race.  Pretty much all the forces that rebelled against Volrath and Belbe were either Elf, Human or Kor.  Though the Kor didn't actually do much.

[TreeSmoker]

Phyrexia? Everything mechanical.

[Rass]

Phyrexia? Everything mechanical.

Phexrian vs the coalition.

[Remillo]

Phyrexia? Everything mechanical.

Unless you count the use of Human flesh in building Phryexians...  And originally, they were Thran, but we don't know enough about them to say if they were human or not.  Maybe they get to that in the Thran novel, but I haven't gotten to that one, yet.