Because Arabic is the language of the holy Qur'an not Hebrew or Aramaic, and the original language of the verse of the challenge you are debating on is in Arabic, but the meaning of it was translated into different languages by HUMANS, just to make it easier for people to understand the meanings of verses......Do you know Odion that Muslims "Must" recite the holy Qur'an in Arabic? Even if it was so hard for them to so. (They will be rewarded for trying, as prophet Muhammad PBUH said).
Also one of the many Miracles of the Qur'an is its language...Besides the very obvious difference of the language of Qur'an and the language of Hadiths.
Edit: I just want to clarify the last point, I mean that the Qur'an contains the verbatim words of Allah SWT, while Hadiths contain the message of Allah conveyed to people by the prophet's own words.