Yeah, your comments weren't quite at the level of the others for sure.
But the business argument or the "it's aimed at boys"argument just simply don't appear to fly. The idea that these magazines are specifically aimed at particular genders (and to a large extent age groups) is less and less important every year. Maybe a decade or so ago, young girls felt obligated to read shojo, young boys shonen, older boys seinen, etc., but that's definitely not the case now. Those identifications are mostly tradition now than anything else. From a business standpoint, marketing to as many possible demographics with one item is generally the goal. How could it possibly be bad business to aim the for the other half of the population?
It is bad business strategy to aim at to much!
You're confusing, which people like your work and what you target. They are totally different things.
If your work is good and has a lot of quality and has luck with marketing, visibility and word of mouth, then it will be loved by everybody or at least a wide group of people.
But when you're making and start to expose your work, if you target to much you end up not hitting anything. So having focus is something important, and not just for manga, but for any business.
Good example of this is the recent Sunrise separation. Now Sunrise has a "spin-off" company, Bandai Namco Pictures, that handles all the family and kids franchises of Sunrise. So now Gintama, Aikatsu, Tribe Cool Crew and others are part of Bandai Namco Pictures and not Sunrise. This was done with the objective of having a better focus in terms of target audience and with that a better utilization of the series franchises.
Now about not existing girls main characters in Jump. That is not just a jump thing and also not just a Manga thing either. Normally in books, movies, theater plays the main character is a male one.
Like it or not this is something that had been for a long time and only a few number of authors, and when targeting some audiences(shoujo, romance stories, ...) will try to change it in their works, and less in a Shonen Magazine.
But there are always exceptions to those rules. Like in Medaka Box(I didn't watched the anime nor read the manga, so I don't know if it is mainly ecchi XD).
So basically is not like a Jump editor will reject your work just because it has a female main character, but probably he will not be an enthusiast of that idea.
Also, if the reason of having a female main character instead of a male character is just to be different, then probably is better to keep with the male main character!