I think that the script usually comes first, then the cast tbh
There was a time that was true. It isn't anymore. National Treasure 2 shot with less than half the script written because the cast had prior commitments and they figured they could fix it in post. The Devil's Own famously started shooting with only the first act written and that was 20 years ago.
Yeah the script should always come first so if it's written by a man already the female character suffers unless he has a woman actively helping him. And then you have the actresses themselves who are chosen primarily for fitting into a very limited looks profit of western beauty. Male actors are allowed a wider range of physical and facial features and I feel like are given more weight for their acting ability as opposed to pure looks.
As a man whose screenplays regularly feature female protagonists, I take exception to this. Actors are chosen for profitability. Full stop. You've heard of A-list, B-list, C-list actors? That's actually a thing. These are metrics determined by independent accounting firms to determine the likely financial impact of any given star in any given role in any given market. These scores and metrics are actually used in prospectii when getting films funded. And of the films you've seen, the majority of them are written by an insane plurality of writers, the majority of which will never be credited (because WGA rules deliberately obscure the reality of the process). Yes - the overwhelming majority of them are white men under 35. But the idea that a white man under 35 is incapable of writing a woman well enough to satisfy an executive looking to make a chinese boy happy is absurd. Finally, actors drive movies. Salt was a black list screenplay starring a dude until Jolie grabbed it and decided to star in it. For a while, Leonardo DiCaprio's people would guarantee that Leo would read your script if you gave them a million dollars. Hancock was written in '78 and didn't go anywhere until Will Smith decided to be in it. Unforgiven was written in '72 and went nowhere until Clint Eastwood decided it was time. Hollywood is a deeply imperfect place but laying the problem at the feet of screenwriters (whom Julia Phillips famously called "the ni__ers of Hollywood") because "men can't write women" is absurd.
I don't the the experience with the process that you do so my perspective is coming from what I see when watch TV shows and movies. It seems to me that female characters are often not well fleshed out, they have odd dialogues, or motivations and seem behave as if the writer wrote that part for a man and then cast a female in that part. Now maybe that's just a byproduct of the focus groups saying a character was too strong for your Chinese male but it sure seems to me like that would have started in the writing stages.
A screenwriter friend of mine once said that describing a screenplay as a "blueprint" for a movie was horribly inaccurate. He likened it more to the travel guide abandoned in the hotel, that thing that you purchased with a great deal of enthusiasm and which may very well have actually gotten you on the plane and to the beach, but by the time you were there you had more important things to do than stick to the plan so while the book may be full of highlighted passages and dog ears, it really has only a tangential relationship with your vacation. Granted, he's jaded. But he's also one of the highest-grossing screenwriters in the history of the medium. The simple fact is nobody listens to the writer. If the actor decides to change lines on set, they do it. If the director decides to change dialog on the fly, they do it. I have a friend who texted me from Paris saying that they had until they landed in Romania to cut 30 pages out of the script. He'd never even met the writer. I have another friend that couldn't come up with dialog on the spot when the director called him from Thailand at 3am local time so the task of rewriting fell to a local PA. I have another friend who routinely draws things that his director asks him to draw, then those things are given to the CGI people, then they're given to the writer to figure out how to make it work. And I have another friend who was flown out to rewrite some scenes on Pacific Rim while it was actually filming, even though he'd yet to have a screen credit, and they ended up using one line of dialog. From about four different friends I've heard the stories of how Producer X decides he's going to do a movie on, say, Teletubbies, so he calls in the top 80 screenwriters for pitch meetings, and he has his assistants take notes while he surfs Facebook or whatever, and then they put together their list of the best Teletubbies ideas out of those 80 pitch meetings and then they pay the assistant union scale to write it. And he's psyched to do it. Because now he's got health insurance. And after his agent takes 15% off the top, and his manager takes 20%, and his lawyer takes 20%, he's making about $60k. Which is the first income he's had above minimum wage, which it took him 3 years to start making, and which he'll never see again because the next time the process is run, he won't be the assistant anymore. He'll be too expensive. Theoretically, you can blame "the writing." Practically, nobody writes movies anymore. They're mad-libbed by committee on the fly.