@Justin1039 In Airbnb terminology, "Long Term" is a stay of 28 days or more - this is only important because that distinction changes the cancellation policy that applies to your booking. For a 21-day stay, the applicable policy depends on whether the host has "Flexible," "Moderate," or "Strict."
The guest refund policy for travel issues that aren't related to COVID-19 travel restrictions is summarized here: https://www.airbnb.com/help/article/544/ . Basically, if you arrive at the property and it's unclean, or an amenity or (in your case) safety feature is missing, your first step is to contact the host and give them an opportunity to remedy it. If that doesn't happen, and as a result you vacate the property, you have grounds for a refund.
It sounds like the bigger problem for you was that you were uncomfortable with the neighborhood in general. This is not officially considered a valid reason to override the host's cancellation policy, as the host has no control over who is hanging out on the street or how you feel about them. I'd personally consider it the guest's responsibility to research the neighborhood when planning the trip, but I realize there are some things you can't know about a place until you get there. Do take a close look at the listing again - if you have evidence that the ad promised features that weren't in place (photos help) that will bolster your case. But I wouldn't expect a successful refund claim based on people hanging out outside the house.
As for the fact that "no one wants to stay in" the apartment, I'm not sure how that would really apply. Last minute replacement bookings are always rare, but we're in a pandemic that has shut down most tourism across the world, spring breakers notwithstanding - even the nicest apartments are sitting empty now.
I do hope you and your wife find a place where you are more comfortable - especially considering how important it is that you stay inside of it for your safety!