That alone took MORE than 16 hours xd. Anyways I didnt even had an idea of what else to add without over complicating stuff, I thought of to add some running humans (some on fire) but that was really hard to do so I added a sandstorm, Thanks btw
Running humans would definitely work there! You can get some free 3d animations (and character models) from mixamo.com. Also, since you kept the camera focus at the close range, running people could look fine in the background, even if they weren't perfect.