The divers, the military, and the engineers aren't the only heroes in this rescue. The film makes this abundantly clear by showing everything else that is going on during the rescue attempts. An early example is the local farmers. When the plan to redirect the water flooding the cave reveals that it will have to empty out over rice crops, the farmers are asked to sacrifice their crops for the rescue effort. While they're obviously hesitant and in no way thrilled by the request, they agree because it is the right thing to do.
Then there are all the scenes of parents, family members, and neighbors huddling together to monitor the efforts and offer support where they can. In high-stress situations like this, it is completely normal for people to lash out and cause trouble. This isn't out of a desire to cause anyone harm or hinder progress, it is nothing more than a psychological reaction to an unexpected situation where lives are at stake.
Thankfully, this doesn't happen. There are a few moments (like when the parents demand answers from the governor) where it looks like things might go this way. Instead, though, most parties involved step aside and let the professionals do their job. While it may not seem like they're doing too much, by keeping to the sidelines, they help ensure that the operation can proceed smoothly. In this case, "not helping" actually helped.
