Python does well for several reasons.

Some that come to my mind: its versatility binding native code and its easy-to-fit in your brain mental model for many tasks. The fact that you can script with Python without a compilation step also helped a lot to spread its popularity I think.

The way you define the entry point function is so bizarre I assume scripting was the original use case.

Could be. But it also gives you the flexibility to set tests inside the module files.