Proto human ancestors were also far more capable than we give them credit for. There is archaeological evidence that, possibly as far back as 2.5 million years ago, human ancestors were harvesting specific types of stone in one location before transporting it over seven miles away to a different location where it was being processed. That is vastly beyond the complexity of what most people think homosapiens were capable of only 100k years ago.
People didnt have to build a society in the exact likeness of modern humanity for it to be vastly complex and advanced in its own right
PhDs are always that precise given the nature of how the levels of academics work.
A bachelors degree involves a lot of general education even though you also do choose a major as a kind of specialization. Having a bachelors degree does imply some increased level of overall knowledge. This leads people to assume that the same is true for even higher education, but it isnt.
A masters degree is virtually entirely specialized, although still referred to in some general terms like majors are. But ultimately ones thesis and specific aims within their field of study define what their masters really is about.
A PhD is primarily a continuation of that focus and expertise that was established in a masters thesis program. So there are only PhDs in extremely specific concepts. Even though we might call someone a doctor of sociology or history or whatever, they really only have doctorate expertise in something hyperspecific
It doesnt help the confusion that medical doctors are effectively the opposite, as a medical doctorate requires a ton of knowledge across a wide number of fields, although they can then further specialize just as much