I'll be glad to see a larger story set in the same world. :)
The first thing I would say is that there is a bit of a missed opportunity here. If you wrote this more from Jetta's perspective, whether in limited third person or second person, it would be a lot more powerful. You could start with her fear, grief, and isolation as she's dragged to the gates of an intimidating city and abandoned there. She's only know what she'd heard of Redlion, and that could be skewed. Perhaps she sees the flags as a broken promise, or ironic. Or, maybe she sees them as hopeful, a promise of a better life and a fresh start. It depends on her personality.
We'd be introduced to the thieves, eventually, through her.
But even when we get to Jetta, her description is at arms length:
"Walking with them was a girl with pitch black hair, worn in two long braids. Her faded dress was threadbare and patched, and her green eyes were sad as they took in the sight of the city. She had dark rings under her eyes as if she hadn’t slept, and she looked as if she hadn’t had a full meal in a long time either. "
If you switch this out of a distant God narration to closer in, it becomes much more evocative:
"Jetta stumbled to keep up; her legs were tired of walking after the long march through the night. Her threadbare dress did little to keep out the early morning chill. The grand city coming into view loomed over the plains, its towers casting deep shadows in the red dawn light, transforming the buildings and walls into a grimacing facade. Her stomach knotted, but she didn't dare ask either of the woman for a piece of bread. Griselda, especially, would be furious. Instead, she sucked on the tip of one of her long braids. The swallowing might fool her belly for a few minutes, at least."
Instead, we start with some heraldry and then get a bit of a technical overview of how the city and the thieves operate. Not bad information, but it's set dressing and information better saved for later. It's also a little unrealistic, as both the city and thieves are portrayed as basically noble or well-intentioned. (Or maybe it's just my own personal pet-peeve to have giant "we only defend, and we take care of our people" cities, since in most feudal societies to get a large city with villages dependent on it would require some attacks over the years. And even if a kingdom has noble intentions, it rarely pans out perfectly due to politics. And it's doubtful a city with a powerful justice system would let even "robin hood thieves" alone. A city that claims to defend its people and be just, but willingly lets the citizens be robbed so long as a few worse criminals are taken care of, is more hypocritical than noble. This might happen in a smaller town where there aren't enough guards to deal with crime, but it's hard to imagine happening in city as prosperous and committed to justice as Redlion is made out to be.)
Overall, it's well written. The setting and plot sound promising. I'd just recommend, again, follow Jetta and her perceptions through the story - at least, if she is supposed to be the main character. It can also help to do go back and do some line editing later to refine descriptions (you rarely need to say "looked like," and it's better to describe a bit of a motion or expression, such as "sneered" or "face hardened" than summarize it like "cruel expression.")
Well, it is called PROTECTORS of Redilion
Although yes, there probably should be some tension between the two factions. It's pretty common for two groups to have common goals and still have conflict over means, idealogy, etc.