You certainly are making good use of the Mass placement tool, which allows you to place a great variety of 3D models and bring randomness and uniqueness to the scene. But when it's time to animate all of these 3D models, the Move and Advanced move effects are not the best options. Instead, you need to use the Mass move effect and, as shown in the following screenshot, it's not that difficult to utilize:

Placing the path is the first step you need to perform and you are not constrained to a single path. The path you create sets two important aspects: the length of the animation and its direction. But there is one essential point that you need to keep in mind in order for this effect to work, which is that the 3D models need to be on top of the path (the gray strip you see on the screen). For example, in the previous screenshot, one of the men was left out of the path and, for that reason, when you play the animation he will stay in the same position...