I also think that it needs to be considered that very few women make it to the top echelon in sport at an older age like this *because* of the timing of child-bearing years. Think of all the women who bow out in the 25-30 age bracket because its time for many to think about children and career. Women on average have 10-12% of their eggs left by age 30. If you hit 25 and you're still not making US teams, you probably consider moving on a bit more quickly than a male who performs similarly might. Not to mention if you haven't chosen a career path that actually makes real money, you better get to work because most female career paths earn a bit less than males would and you're starting in a deficit (for admittedly more complex reasons than just "sexism" but not a relevant part of the discussion here).
So we likely have the problem of a very small sample size of women that have attempted to resurrect a running career post-babies, which is why this feels like such an outlier, with no other precedent to compare to. I don't know if professional women at the top who had babies and came back are a fair comparison either. Of course you will see little to no gains in those cases because they were already maxing out in training and competition and typically time having children slightly post career-peak.
Keira was a 3x All-American at AU in cross country and once in outdoor track. Has anyone been paying attention to the level of elevation of track times for top collegiate women in the last 10-15 years? I ran collegiately 2004-2009 and I'm pretty sure 16:28 qualified for the indoor 5k my final year. That was the 67th best time last indoor season. People are flying all over the country to run on oversized or banked tracks, or over to super fast time trials on the West Coast to post some incredible times. Thats just not something most teams did (or could afford to do) early 2000s when Keira was in college. She was probably posting her best 5k at 10 pm at the Penn Relays on distance night when the 10 spectators still there are freezing in the stands. So I wouldn't rush so quickly to write her off as some nobody in college. A quick google search also reveals she was a 3.8 GPA in Mathematics (and maybe Computer Science?) so she was likely working pretty hard at multiple things and not coming anywhere near max potential in college. Maybe she would have been running these types of times (or faster) a few years out of school if she had been a part of something like the Bowerman Babes back then, but it didn't even exist yet. I'm guessing there were very few training opportunities for non-NCAA champions in 2006. So most people in her situation back then would have tried to stick around their college coach, supplement with a part time job, and like her, end up bagging it after getting injured. That said, I think Centrowitz's training was always very conservative from what I remember others saying so now with a healthy, strong body and all her ducks in a row mentally, physically, etc, it seems possible to me. For these and other reasons, I'm actually buying these performances.
I don't know Keira personally, I'm just a fan of the sport and LetsRun and busy these days chasing around a 1 year old with another on the way so its kind of fun to live vicariously through her when all I can muster is a 20-30 minute run with the jogging stroller at 9 minute pace.