The humans are the unchanging machines in QC world.
Humans are unchanging machines in the real world as well. Oh, sure, there have been advances around us that may make us seem different - the industrial revolution, computers, space travel, etc. - but humans themselves are still just as human as they were a thousand years ago. And if we're not actively involved in those changes around us, it's terribly hard for us to keep up.
I was making a joke that they don't age.
Ah... Forgive me.
Of course, only a few years have passed in-universe, so there's not a lot of aging for them to have done. With the exception of Amir, and the various parents, everyone is still under 30. I do find it interesting that Faye seems to look even younger now than when the fight club closed up. Clinton, on the other hand, looks more mature. I believe that is related to their circumstances. Faye, it seems, is meant to look more vulnerable, so the badass tough bitch that worked at the fight club had to soften up. And Clinton... well, he actually
has matured considerably in the course of his recent events. Both Emily's and Dora's hair is growing, so there's definitely some time passing.