Apple gets this spot on by having an icon represent the action actually being performed, i.e., sending some information somewhere. That could be to yourself (a bookmark) to another person, a group of people, or the public at large. It doesn't really matter.
Many of the others are trying to represent the abstract concept of "sharing", which doesn't fit the use case at all. That's why those icons don't make any sense. Others are representing specific technical concepts like graphs that again, only make sense for certain specific uses and aren't especially intuitive.
In many ways, it makes sense to outsource this kind of design to someone that doesn't speak any English and run the brief through a translator. That way you're forced to explain the concept that the icon needs to represent, instead of having the icon represent the English word that happens to be (perhaps wrongly) attached to the concept.
Distilling the concept down to an arrow pointing outwards to represent sending something is the kind of minimalist, universally intuitive design that Apple are often brilliant at. Approaching the design task like an engineering task is likely to lead to this as the optimal solution. I find it endlessly interesting that good designers tend to do this intuitively, in spite of not thinking anything like Engineers, whereas Engineers tend to do the opposite if forced to do design.
Many of the others are trying to represent the abstract concept of "sharing", which doesn't fit the use case at all. That's why those icons don't make any sense. Others are representing specific technical concepts like graphs that again, only make sense for certain specific uses and aren't especially intuitive.
In many ways, it makes sense to outsource this kind of design to someone that doesn't speak any English and run the brief through a translator. That way you're forced to explain the concept that the icon needs to represent, instead of having the icon represent the English word that happens to be (perhaps wrongly) attached to the concept.
Distilling the concept down to an arrow pointing outwards to represent sending something is the kind of minimalist, universally intuitive design that Apple are often brilliant at. Approaching the design task like an engineering task is likely to lead to this as the optimal solution. I find it endlessly interesting that good designers tend to do this intuitively, in spite of not thinking anything like Engineers, whereas Engineers tend to do the opposite if forced to do design.