In Golarion, the 'god of humanity,' Aroden, had the longsword as his favored weapon, and the 'inheritor' to his mantle, Iomedae, also has the longsword as her favored weapon.
Still, as has already been mentioned in this thread, the longsword may be relevant in Avistan, but the scimitar is the weapon of choice to the east and south, and by the time one reaches the Mwangi expanse, swords in general are likely to be less common than spears, making the longsword a bit too regionally specific to be a perfect 'generic human' weapon of choice.
If spears didn't generally blow in D&D/PF, I'd totally vote for the spear, to give humans a weapon that doesn't tread on the elven 'bow and blade' or the dwarven 'hammer and axe' niches, and a weapon that's likely to see use from the Mwangi Expanse to Arcadia to Qadira to Taldor to the Lands of the Linnorm Kings.