Here’s a take on the characters of Arrival per their archetypes:
Protagonist; Louise Banks
Nemesis: Agent Halpern, Private Lasky
Attractor: Hannah, Ian Donnelly
Trickster: General Shang, Colonel Weber
It seems like the Aliens are Nemesis figures — they certainly wear the nemesis ‘mask’ for the first part of the story and into Act Two — but in fact, they are Mentors, conveying key ‘wisdom’ for the human race generally and to Louise specifically (re Hannah), AND helping Louise to hear — in the future — what Shang says to her which results in the cessation of move toward annihilation.
Once Louise connects with the Aliens, the Nemesis ‘baton’ gets passed to Private Lasky and his assault on the Aliens, then Agent Halpern who become increasingly more antagonistic toward Louise.
Re Attractors: Characters most connected to the Protagonist’s emotional development. Ian as her lover. Hannah as her daughter. And the gut-wrenching choice: Go forward with Ian and have a baby, knowing (A) Hannah will die young and (B) Ian, who cannot handle that tragedy, will leave the marriage. No matter the negative trajectory of both relationships, the fact is Louse connects with both on an emotional level which is what compels her to agree to move forward with her future despite the horrific emotional pain she knows she will have to bear.
Aliens as Mentors. Of course! On so many levels, most specifically they are instruments for communication to humans and to cause Louise to makes the connection to Hannah.
At first, Shang and China are part of the world-wide team to try to figure out what the hell is going on with the alien ships. However he is a military man and so default mode is war. Fortunately circumstances evolve so that he intersects with Louse at that fateful ball.
Colonel Weber perhaps less a Trickster in that he lures Louise out to the remote movie-making site where the alien spaceship hovers overhead, generally supportive of her, and yet there are times where he doubts her grasp of the alien language.
None of this is etched in stone. Your take may vary. But there does seem to be something going on re archetypes in this story. The above represents my initial thoughts re characters. How about you?