The other thing to look for is what actually works fine and what doesn't in your less than perfect shots.
For example the signs and building facades in the background are IMO at a very usable level of exposure. Given your expectations, the people are just underexposed, too dark and not enough detail.
Simply adding exposure to the whole shot may make the shot workable but it might also place the background too light in the print.
That's a "problem" or "defect" in the lighting of the scene, not a problem with you camera or the film.
One of the most important lessons I've ever learned was taught to me by shots like yours, it is that my backgrounds and my foregrounds are regularly lit differently than what I need for the print I want. That's why I use my flash units a lot.