In the project I am working on, the main race in my setting has the body plan similar to a primate, and has somewhere between a moderate, or highly arboreal lifestyle. (Haven't quite settled on this yet) Recently, I stumbled upon the topic of human throwing, and how large of a role it played in human evolution. Essentially, changes in our shoulder structure allowed for more arm mobility during throwing, allowing us to hunt and consume a higher quantity of meat in our diets, which helped in brain development. The problem I ran into with this, is that I want my race to maintain both arboreal-proficiency, and the ability to accurately and powerfully throw, which so far appears to be two contradictory actions.
With an ape-like shoulder structure, where the arm's hinge is positioned upwards from the shoulder, it allows for good swinging and climbing, however, limits the upper arm's ability to rotate during the throw, making powerful throws essentially impossible. With a human-like shoulder structure, where the arm is perpendicular to the shoulder, it allows the upper-arm to greatly rotate, and therefore allows powerful throws, however makes humans somewhat mediocre climbers, at best. I am aware that humans are able to climb, and pretty impressively too, but compared to apes, there is essentially no competition, and physically, humans expend much more energy doing so. Is there a good middle-ground structure that allows proficiency in both actions? Or would a potential shoulder structure like this just lead to mediocrity in both?