No, no, see, you're trying to use logic here. That won't do. 
That's the way it ought to work. But that's not how it actually works, and that's one of the problems. If you do the civil war quests before the main quest the Jarl suddenly and inexplicably knows all about the events at Helgen.
And the whole business gets even more ridiculous. The Jarl not only knows about Helgen before he's been officially informed of the events but your dialog informing him about the events is right there in your dialog options. So we have an incredible screw-up: after the Jarl tells you he won't accept the axe until you deal with his Dragon problem you can then choose the dialog telling him for the first time about the Dragon.
This is a bug, pure and simple.
If the player does the main quest first the Jarl learns of the Dragon attack for the first time from the player. So it would make sense that if the player never informs the Jarl of the attack the Jarl would have no way of knowing about it, right? But, no. If the player does the civil war first the Jarl suddenly develops

That's the way it ought to work. But that's not how it actually works, and that's one of the problems. If you do the civil war quests before the main quest the Jarl suddenly and inexplicably knows all about the events at Helgen.
And the whole business gets even more ridiculous. The Jarl not only knows about Helgen before he's been officially informed of the events but your dialog informing him about the events is right there in your dialog options. So we have an incredible screw-up: after the Jarl tells you he won't accept the axe until you deal with his Dragon problem you can then choose the dialog telling him for the first time about the Dragon.
This is a bug, pure and simple.
If the player does the main quest first the Jarl learns of the Dragon attack for the first time from the player. So it would make sense that if the player never informs the Jarl of the attack the Jarl would have no way of knowing about it, right? But, no. If the player does the civil war first the Jarl suddenly develops

