I think "incompetent" is a somewhat-harsh word to describe something that I think is really there in Jack... It reminds me of what Jake says in one of the interviews in the bonus features on the DVD, where he interprets Jack as "trying" all the time. I think this is very perceptive... I think Jack is desperately trying to be a model cowboy and really is striving to do his best even in things he's not so good at. We see Jack make mistakes (like missing the coyote and spilling the beans, etc.), but I don't really think these "flaws" indicated "incompetence" (although Old Man Twist probably saw it that way)... I think these things are expressive of Jack's personality in some way. Perhaps missing the coyote is a sign that Jack is too high-spirited or impatient to do something like shoot an animal. Or maybe it means it's not really "in" Jack to kill or hurt something (even an animal) very easily. OR maybe it's foreshadowing about his death (supposing that he was murdered)... Jack is unsuccessful here at dealing with a predator (perhaps that can be stretched to his inability to escape predators in the murder scenario). Anyway, I also think we are shown moments when Jack is actually very successful and "competent". He's the one with more herding experience, so he's the one who leads the flock. We see him win a rodeo. Lureen tells us that Jack is a good combine salesman. He's also good at being a caring father (worrying about Bobby's tutor, etc.). And, we see how good he is at drawing Ennis out and bringing genuine happiness to Ennis, etc.
LOL, I went searching for a pre-existing thread about Proulx's use of symbolism in her writing (still thinking a lot about the "is a cigar just a cigar" topic). And, I landed on this one.
The first post in this tread brings up the part of the BBM story that's been on my mind all day regarding Proulx and a really blatant and complicated deployment of a symbol in her language. Right at the very end of BBM she describes how a spoon can also come to be seen as a tire iron.
"...the can of beans with the spoon handle jutting out and balanced on the log was there as well, in a cartoon shape and lurid colors that gave the dreams a flavor of cosmic obscenity. The spoon handle was the kind that could be used as a tire iron."
I feel like this description is like a key to understanding Proulx's careful use of symbols and is like a key into understanding (perhaps) other and more nuanced symbols in her writing. I feel like this is equivalent to the moment in the film when Aguirre says "look what the wind blew in", which acts like a key to becoming aware of this and other symbols.
