[@ERode]
They did, but obviously  not enough to destroy the skeleton, as it's still chasing after her awkwardly.

[@Crusader Lord]
There already exists a class for that. It's called a bard. They can do fighting, magic, archery and thievery, but not as well as any of the other classes who are more focused on their respective job.

Honestly, though, your description of the 'Hero' class makes it sound like they're rather skilled and good at anything. It has no weaknesses or shortcomings other than not having access to the more specialized capabilities of the classses it mimics. Which isn't really a drawback when you can do everything well, to be honest. If you can't beat a warrior in a straight up fight, then just fling a spell at them. If you can't out-magic a mage, just shoot them down with a sneaky arrow. If you can't beat a fleet-footed fencer, smack'em with your shield bash.

I generally do not like, on a personal level, jack-of-all-trades characters, because they simply reject the concept of working together and being a part of a team. Which, in a roleplay scenario, is rather counter-intuitive. You're free to play one, of course, if that's what you want.