As far as I know Python is one of the main programming languages used in information systems along with Java, C++, and a few others.
Python's uses are very broad because of its easy syntax, it is used in ML, but also Data Science, frontend, backend,etc... It may not be the most popular language in some these, JS is more popular in frontend for example, but its used in a lot of different fields.
The largest part of backend and most programming specializations is understanding the computer science and logic behind it. Learning programming languages isn't the most difficult part, so your starting language is important, but not as much as you think. You need to pick up many languages as the job market changes, but you'll always need the same core computer science knowledge. But, Python is definitely a great starting point for backend in case you want to switch specializations since its so versatile.