It's not that you should factor them out but if C is actually doing the work you can call the same excellent libraries from Ruby too.

e.g. Numo for NumPy or Ruby-Polars for python polars.

I haven’t used Python in years but from what I’ve understood by reading other comments, factoring out C-based libraries would rule out a large portion of what makes Python so popular. Especially on the scientific side.

So I think you’re right.

How is a C codebase a part of the Python ecosystem?

More accurate statement would be: Python is piggy-backing on hugely successful C libraries and claims big performance on their backs, IMO.

Yes, but if you're comparing language performance that's important.