Akane is the most commonly recurring main character of the Psychopass series, as mentioned by Fluffycow. Sybil is definitely NOT a protagonist, it's the antagonist lmao. Dunno how you could get the impression it's anything else.
"Protagonist" is not a judgmental term, but simply describes the person playing "the first part" (both in importance and sequence). Villain protagonists are a thing, y'know. And one could reasonably argue that Akane isn't the Season 1 protagonist, but Shinya (the same way Watson is the viewpoint character, but Holmes is the protagonist). Yet generally I'd go with the label "Ensemble cast" due to the many pieces involved in Sybil's game.
I should say that I'm a huge fan of LycoReco myself, I know some people don't care for it and fair enough if you're not a fan, it's definitely not a perfect series. However I do sincerely enjoy it and love the series, the main duo are one of my favorite ships.
Personally, I like the many cute LycoReco doujins over the anime. The café half was solid and could stand on its own. The clandestine paramilitary half is something I try to ignore exists. However, I'm now wondering ... what is the chance that the near-future Japan of LycoReco is actually the past of the Psycho-Pass one? Sybil canonically had AI predecessor systems, and the whole portrayal of the population as docile, ignorant and best steered through extrajudicial executions resonates in both works. (I guess this is better followed up on in the Cafe thread though.)
Also I think youth in general is popular for humans. Growing old is scary, and you have a lot of classic stories focusing around concepts of youth and chasing after it. [...] Japan has a lot of problems with overwork from my understanding, which even leads to some isekai being started via death from overwork. Which I think extends globally in general, there's a lot of struggles with economy, stressful politics, work. Being young and not having so many worries is definitely appealing to many, and nostalgia is also powerful for many.
For me I'm often able to find a good mix of both maturity and youth with anime and manga. I watch and read a lot of things across many genres, and I've found that even stories focusing on young characters can explore themes of growing up in mature and interesting ways.
Are you sure about the "anime" part? I have the feeling that this decade's anime overwhelmingly has casts that would count towards the Young Adult genre in the west. (The absence of western YA animation is a topic for another day.) Looking through the upcoming anime season for series with main characters/cast past their twenties yields me Uzumaki (Junji Ito horror adaption), 365 Days to the Wedding (actual romance!) as well as Neko ni Tensei shita Ojisan and Hyakushou Kizoku (both Comedy), plus two "old man rediscovers joy in live through daughter-like figure he mentors" stories. That's from over 60 anime airing. (Admittedly, there's hardly and Josei or Seinen amongst them. Not sure if my source is biased or that's the direction the industry goes.)
It's honestly kind of sad, because that means we get no stories of "real adults" (= anyone older than me) having any character growth. Do you lose the right to have dreams when you turn 30? It really says a lot about societal expectations dictating the remainder of your life. Thankfully manga and other literature cover those age spans, although fan work is of course shaped by its source material.