I started trying to type of a post to explain this but it's kind of confusing an complicated so I'm trying to break it down as simply as possible. Basically:
- Humans are a species.
- "Baseline" humans are the "pure" humans like those of real-life Earth. For a while (particularly on planet Nepleslia) they were considered rare enough that scientists wanted to study them. Now they're becoming more common due to genetics projects. Most baseline humans on Yamatai died in the Great Plague of YE 08, causing their low numbers.
- "Nepleslians" (as in the species) are a type of human subspecies that is not purely human (e.g. mutations, sharing a bit of DNA with aliens, etc). It's also used as a general term for any humans that have their family roots going back to the colonists that settled Damasica, Kennewes, Nepleslia, Rok'veru, and other early human-settled worlds in this area of known space. For a long time, all humans in SARP were considered Nepleslians.
- "Baseline" humans are the "pure" humans like those of real-life Earth. For a while (particularly on planet Nepleslia) they were considered rare enough that scientists wanted to study them. Now they're becoming more common due to genetics projects. Most baseline humans on Yamatai died in the Great Plague of YE 08, causing their low numbers.
- Since Nepleslia is no longer part of Yamatai, it's become less appropriate to call a Yamataian human a Nepleslian, unless they're from a recent Nepleslian heritage like Taisa Rufus Sydney, who used to live on planet Nepleslia. This is because it can be confusing with regards to nationality or an improperly-applied species label when used on baselines. Instead, the term "human" is making a comeback in the YSE.