An epiphany about Windows RT!

It just occurred to me that the presence of the desktop with a few applications(explorer, minesweeper, Office) means Microsoft somehow ported Win32 API to ARM! Now only Microsoft possesses a Win32 to ARM compiler which means even if you jailbroke a Windows RT device you'd not be able to run an existing x86 app. It would just sit there as a bricked binary. Someone tell me I'm wrong about this. How else did they put all those legacy apps on Windows RT?