There are various ideas that come to mind...
A really coarse analysis would say "reap what you sow" and the predator becomes the predated. But it seems far more complicated (and interesting) than that.
What seems to be human at first ends up being extremely alien, and it's clear the alien really doesn't grasp humanity. In fact, early on, it's clear the aliens are capturing humans as some kind of food for their kind, with the protagonist as a form of honey pot that lures potential victims in and capturing them intact... we are not individuals, we are simple commodities to be acquired to sustain another race's life.
However, in the process of interacting with humans and wearing human skin, the alien begins to identify as more human without really understanding what that means. At some point, she frees a potential victim and finds she can't continue with her assignment, even though she really doesn't understand why yet. (I think there's a fractured mirror image occurring right after this, where she looks within and her reflection is all distorted and broken into pieces.) In fact, she breaks with her own kind here -- she purposefully goes "off grid" and her handlers try to clean up the mess but can't track her down. it's not clear what they would do if they found her.
The next part of the movie addresses her attempts to grasp humanity and do things / try things that are 'human.' She tries eating (which doesn't work because she is not human), she tries companionship (relating without victimizing, which is confusing to her), and ends up trying sex briefly not knowing what it is and being shocked at what follows. (And her anatomy does not work for this either, despite looking female on the outside.)
She then flees into the woods, where she ends up being victimized herself by a human predator. First he attempts to victimize her as a human female would be victimized. When he realizes that she is not actually a human female (when her skin rips open), he ends up victimizing her differently. She is vulnerable because (1) she is in a state of personal flux and unsure/doubting of who and what she is, (2) she is "off script" and her only power -- that of "allure" -- is no longer usable, and (3) she is actually an "other" and terrifyingly so, so she brings an immediate response of repulsion, much as a human would smash a spider with a shoe that had encroached in the territory of the human in question. If she had maintained her original identity, and/or continued to do her job, and/or hadn't been detected as alien, she would have avoided the violence or only suffered what was typical for humans versus what amounts to total destruction down to the particle level.
what conclusions are we supposed to draw? Well, I love the ambiguity of it as noted above, there's a lot going on subtext-wise. And on one hand, the aliens seem like the monsters at first, preying on us, but then the story flips at end. The "monster" ends up having a bit of a conscience and is trying to figure out who/what she is (I'm not even sure about gender, it's just her role and human appearance is female), and this makes her vulnerable to being preyed upon in return -- the humans end up being as deadly as her. Note how TERRIFIED she also is at this point, realizing she is actually vulnerable. This is a new thing for her too, and she is not sure how to respond to the threat -- just that she is scared.
The aliens were also killing humans for practical reasons (although I don't really know whether they were a dying race or just self-absorbed like the planet farmers from Jupiter Ascending), but the protagonist is murdered mainly for being "other" without any other reason. And it's kind of remarkable since it comes off as a hate crime, even though we just watched this alien prey on humans for awhile; it's just we saw her stop doing that and become more vulnerable and curious about this race she was victimizing and what it felt like to BE human... and meanwhile a human when realizing she is an "Other" immediately murders her in painful brutal fashion for no other reason except repulsion. And I love how she is unmasked during this, so we are still forced to confront how non-human she is, yet feel like she is the one being victimized.
Different groups of being are "Other" to each other, but we are able to show more compassion the more we become aware of the Other as a being of sorts. However, some people are not able to see the "Other" as a person and out of fear or disgust over the differences feel a compulsive need to destroy. I like how humans and the aliens here are kind of on the same turf -- neither is really elevated as wiser. I think some of the humans she met would have the ability to accept her; but some did not. And her own individual growth suggests that some of her race could actually grow to accept humans as well.
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