"You can't just say whatever comes into your head. That's bad talking." Hank (Paul Dano)
Swiss Army Man is not Weekend at Bernie's, despite the animated corpse, Manny (Daniel Radcliffe), nor is it Cast Away with its benign Tom Hanks character and soccer ball Wilson. Rather it is as imaginative and unsettling a fantasy as you will see in your recent memory. The corpse (Daniel Radcliffe) eventually talks (albeit perhaps in Manny's mind only), and as the above quote suggests, maybe too much.
Marooned on an island, Hank is suicidal to the degree that he tries multiple times. Life has not been agreeable especially in his now lost situation. Enter corpse Manny, whose initial introduction is a body still filled with flatulence. Okay stuff for pubescent boys in the audience who can identify with the humorous properties of farts.
However, as in all good allegory, this film is conscious about the figurative relevance of those bodily functions, even boners from a dead man. As you already figured out, this body carries the weight of allegorical implication, mostly confirming that even in the body's basic functions, there is life affirming activity, enough for a seriously homicidal like Hank.
Swiss Army Man has a bunch of utilitarian functions, like the titular renowned knife, to counter the absurdity of life so well documented in the detritus Hanks finds in his lost condition. Cheese Puffs become almost sacred to a hungry castaway and erections are publicly appreciated as evidence of life, especially among the dead.
Dano and Radcliffe are the modern buddy-film icons, clueless about the value of life at its simplest but smart enough to figure it out. The ubiquitous smart phone, with its waning power, has the brief power to engage even a corpse with images of lust and maybe love, fleeting as the images might be.
A foraging bear reminds me that Hank is not as vulnerable as Leo's in Revenant, yet dramatically showing the wit of the two buddies for saving themselves. Nature is always a danger, but survivable if buddies are willing to count on human nature to get them through.
Swiss Army Man is not as oblique as Samuel Beckett's absurd dramas but feels much longer; however, it is Beckett with a sense of humor. It has an accessible figurativeness to please even the most unwillingly interpretive audience.
See this film to help you understand that even the basest human activity is better than the void to which we are all called.
