the shoot out scene works on distracting you and giving you a sense of safety
it makes you think "ok they are on top of things and they can bring it if they get attacked, they can defend themselves and they are capable of defeating any threat.
Since they are seeing creepy things from the beginning and they are being stalked, the shoot out scene works perfectly to make you let your guard down and just think of it as a regular action movie.
Not only are these people living well and safe while theres something creepy in the woods (Something I always think about, those people didnt fear living there or working there, they seemed okay) this lets you think that whatever they will go against cant be that bad.
seeing these people go into their every day lives in the jungle gives you a false sense of safety.
And seeing our heroes dispose of them so quickly and efficiently makes us think that they can succeed or that they are very strong opponents.
the scene is so perfect in doing that, that when the hunt starts it really hits you hard and makes you feel nervous and stressed out because not only does the predator show you that hes much stronger and scarier than you thought, but that our heroes are extremely weak and the hunt even makes you wish those other people in the jungle were alive to join the fight against the predator.
thats the beauty of that shoot out scene. it sets up the rest of the movie so perfectly. it makes you think you are about to watch a regular loud action movie with a lot of shooting but then it turns the tables on you and that shock makes it so much scarier