Looking through Discourse, it’s difficult to find things that are evergreen… 
It’s mostly interesting discussion that is or will be out of date eventually. One exception I think is the About Champions and Heroes post. This has continued to be a guiding document, we have implemented champions into the structure of the Initiatives plugin (each Initiative has a champion), and I believe we link to it from the official docs somewhere.
Other than that, maybe Separation of Powers + Checks and Balances? I know @decentralion has posted this before on Twitter, presumably in part because it captures some of the ethos and thinking around the project. But again, could get out of date.
Don’t know if they’ve already been posted, but I do think we have some long-form articles that could be good. Gotta shill my own (which I do genuinely think is good:),
Also, this is bound to be a must read for anyone that wants a deep dive into the algorithm (maybe not best for bot though if just intro content?).
And these data sciency’ articles diving deeper into the theory:
I also still very much like the first podcast with @decentralion.
Have posted that numerous times to introduce people to SourceCred. I worry a bit that it’s getting a little out of date, but I think it’s generally evergreen. Curious to hear if @decentralion disagrees.