I like that you don’t know anything about the monsters in A QUIET PLACE, other than the things you NEED to know. Namely, that the creatures are blind and hunt by sound, that they are nigh-indestructible, and that they are vicious maneaters. That’s all you need to enjoy the movie. Further details are unnecessary, even superfluous. Discussions in regards to their origins, their motivations, and their true nature are better saved for after the final credits have rolled–like now, for instance.
If I were asked to guess at an origin for the monsters, it would be one of a few things. Either they are extra-dimensional, like the kaiju in the PACIFIC RIM movies. Or else they’re aliens, from another planet. Or else they were created in a laboratory somewhere, genetically engineered, and then they escaped and started reproducing like mad. Turns out, according to John Krasinski himself, yeah, they’re aliens.
Said Krasinski on the EMPIRE Podcast: “They are absolutely aliens. They’re from another planet. Where I developed the idea of them and what I wanted them to look like was most alien movies are about takeovers, agendas, they’re a thinking alien creature, and for me this idea of a predator, this idea of a parasite, this idea of something that is introduced into an ecosystem…it would be like releasing wolves into a day care center…they were able to survive kind of the explosion of their planet and then survive on these meteorites, because they’ve evolved to be bulletproof. Until they open themselves up to be vulnerable, they’re completely invulnerable…[the invasion] happened so fast…I wanted to break all the rules or the conventions that I had seen in alien movies which is like a speech from the president and people deciding how to survive. There was no deciding, it just happened so fast that you either survived or you didn’t.”
And there we have it.