I see a lot of folks complain about not getting help on OSS projects; I also see a lot of people turning a blind eye to people trying to help (however naively it may be). It's an intesting dichotomy.
As soon as you are giving free attention and mentoring to people unable to make a somewhat useful contribution, you are giving up even more of your life for free.
There are people who know how to pick appropriate issues and send PRs with test cases. It might be better to look for them than try to mentor ineffective contributors.
One needs to study on their own, use forums or get in touch in some other way that isn't a PR if they want help. Also, while studying the codebase, finding low hanging fruit is going to be easy. That's where everyone should start.