Some of those words don't seem to be quite right. Let me see if I can fix parts of it. I'll put the edited parts in bold and underlined for you to see what changes I've made.

"Alduin dir?" "(Did) Alduin die?"

"Alduin is no-more. Slain by a man, with the soul of a dov. Dovahkiin."

"You rule our kind now?" "Hi rel un fron nu?"

"I teach them the way of the voice. How did you escape?"

"Mun nis rel zu'u. Alduin dein zu'u ahst vaal." "(A) Man cannot dominate (imprison) me. Alduin kept me at bay."

"Men rule themselves now. We are not their gods."

"You are weak! I will rule them! You will serve or be devoured!" "Hi los sahlo! Zu'u fen rel niin! Hi fen aam uv kos diilon!"

I could have used dilon for the first line, but I feel like the phrasing of that would be too ambiguous, so I went with something simpler. Instead of saying dein as a substitute for "imprison," I decided to go for rel, meaning "dominate," which is a closer synonym than "guard." The phrasing of the last line made it almost seem like the speaker would be ruled instead of the other individual, so I changed rel there to aam, "serve" and added kos before diilon to show that the speaker is not the one who would be devoured. (Not sure where you got "ou" as a translation of "devoured," though. Might have been a typo, but I'm not sure what it would have been.)

All in all, this was fairly well translated! You show promise as a translator of Dovahzul. I'd recommend you making an account here to further learn the ways of the Dragon Tongue! We could use another competent translator like you.