Board Thread:Lore Discussion/@comment-26177830-20150401044533/@comment-121511-20150405013000

Sothas wrote: To be fair, the "mortal" hero isn't so mortal. He's a Dragonborn Shezarrine and a Prisoner. Pretty important dude(et).

Don't mean to imply that the Last Dragonborn isn't incredibly powerful for a mortal, but he is still a mortal, not a God (though that doesn't prevent him from becoming one). It's just an example of why Alduin is far from omnipotent or invulnerable.