For historical reasons (FFI), Python has access to excellent vector / tensor mathematics (numpy / scipy / pandas / polars) and ML / AI libraries, from OpenCV to PyTorch. Hence the prevalence of Python in science and research. "Everybody knows Python".

I do like Typescript (not JS) better, because of its highly advanced type system, compared to Python's.

TS/JS is not inherently fast, it just has a good JIT compiler; Python still ships without one. Regarding security, each interpreter is about as permissive as the other, and both can be sealed off from environment pretty securely.