Regarding Batgirl...I saw that Warners Bros also just cancelled some Scooby Doo thing that cost $40 mil and was already completed.
Completed movies and TV shows are cancelled all the time. There's even a couple infamous superhero ones that were eventually leaked or bootlegged. It's not about quality though, it's more about whether they think they're going to make their money back.
Having said that...while I'm sure BG wasn't cancelled just because it had a WoC and LGBT characters, I'm sure that fact certainly didn't help it in the minds of the execs.