I'l agree with the great David OReilly on saying that realism is probably not the most interesting thing [digital] art can do. Personally i find realistic digital art uncanny more often than not, though it has to do with animation.
I wonder with which source of inspiration you will go for such an ensemble cast? I'd probably crowdsource faces from people who themselves were inspirations, then maybe ask reddit and or lemmy and people here. Some devs occasionally take suggestions from their patrons. Curious Expedition 1 had it's first viral moment with Nikola Tesla pulverising hyenas with the death ray in the savannah, this is how Maschinen-Mensch decided to go with a prominent 19th century figures irregardless of how likely it was for them to even leave the house, let alone to embark on the expedition into the unknown.
https://store.steampowered.com/app/408510/Curious_Expedition_OST__Artbook/
Curious Expedition 1 vs Curious Expedition 2 is also an example of the drastic art style change rather than evoluation of it, which probably made sequel less successful. I find part 1 style clean, cozy, endearing and evocative. Not to say that 80s sungeon crawlers' or delightfully shitty and crudely animated mugshots from Hotline Miami wasn't evocative )
40 faces! Is art-making your fav part? I knew i would be trapped in just drawing or learning to code without clear direction which is why i went for playtesting ttrpgs right off the bat.
I hope devlog about schedule i've shared will help you to complete the project without burning out