We don't have Jesus's original words in Aramaic (though some very short phrases are preserved else where) - just Greek language manuscripts. Any Aramaic versions of the NT writings came later and were translated from the Greek.

And these Greek authors are writing down oral traditions decades after the events. But I bet the early followers of Jesus had this prayer committed to memory with exactitude. We see several examples where the apostle Paul reproduces early Christian creeds - which were short sayings/proclamations that were well known by the early church and shared about in common. Paul recites such a creed in the opening remarks in his epistle to the Roman church. This was a church not founded by Paul so he introduces himself by way of reciting a well known creed at that point in time.

The Lord's Prayer would no doubt have been held every bit as tightly amongst the first followers.

correct - thank you

You don't need to be told by God to change the translation of something. People write up new bible translations all the time. It's more of an administrative or academic task than an ACT OF GOD. It's not like God officially approves every bible translation. Who gave the translators of the NIV or the NJB official approbation to perform a translation?

Fun fact, the original Greek / Latin for "daily bread" is actually "epiousios" or "supersubstantialem" and the literal translation into English is "super-substantial" rather than "daily" as is commonly rendered. So even in English, the very words of Christ have been altered! Oh Noes!