This question was asked regarding Parshas Balak (Parasha named after Balak?), however, I'd like to see a source or reason that explains why the Torah chose these 6 individuals to name the Parsha/Sedra after:
Just listened to shiur by Rabbi Eytan Feiner, who when giving it says that Chayei Sora even though it has a name in it, it not the list of parshiyos that are just names. So I am going to summarise the shiur and hopefully it is understandable.
He says that these 5 people all have in common a turning point in Klal, that excludes the spies and the egel since there is not one person who can represent them. Also Moshe is not given a parasha because Moshe symbolises so much and you can't isolate Moshe to one thing since he corresponds to so many millstones. Also Vayikra there is no name since the Rambam its a continuation of the Matan Torah experience so no major transition take place.
So we start with Noach there is a world before the mabul and a world after the mabul and the person who changes the course of time is Noach with the 7 Noachite Laws.
Next is Yisro where we go from just keeping the 7 Noachite Laws into the 613 Mitzvos. He represents that transition from Exodus to Matan Torah.
The next is Korach where he represents a new transition in Judaism Machlokes, but not just any Machlokes rather the first Machlokes where the Jews actively and loudly challenge the authority and leadership of Moshe.
Next is Balak where he got us right at the end of parashas Balak by getting away from our fabric of מה טובו being modest and destroys our fabric.
Finally is Pinchas where he destroyed and restore the destruction caused by Balak, and being the real leader.
All of these 5 represent a transition in Judaism.