The Media Creation Tool currently serves (Build 19045). Even if you use older command-line tricks with the MCT, you cannot roll back to 1507.
If you successfully download this ISO, be aware of these three traps: windows 10 rtm core single language iso download
Furthermore, the "Single Language" SKU was rarely distributed via MSDN or VLSC (Volume Licensing Service Center) as a public ISO. It was primarily an SKU, preloaded on budget laptops in emerging markets (SE Asia, South America, Eastern Europe). The Media Creation Tool currently serves (Build 19045)