I firmly believe that G-d made the Torah, but I wonder why He refers to himself in the third person, while the Ten Commandments are in the first person?
The Torah is written בלשון בני אדם. It is a narrative that was chosen by Hashem as best to communicate the divine message.
Furthermore, some parts may seem incomprehensible if written in the first person e.g. the first pasuk would read "in the beginning I created the heaven and the earth..." this may leave more questions than answers.
'Getting to know Hashem' is gradually transmitted through the narrative, stories and subsequent lessons we learn.
However, having said this we may never know the reason for the exact stylistic choices of the Infinite.
here's a probable explanation:
The Torah that we currently possess is called Moses' Torah (תורת משה) which implies that it is literally written by Moses. Of course, it is a prophecy and is 100% G-d approved. THis is based on Rambam's 7th and 8th principles of Judaism, that the whole Torah comes from G-d by Moses. (This is unlike the Luchos that were written by G-d Himself and hence the first person.)
So if the Torah used the first person, it would sound that Moses is god H"V and he speaks for himself.
You might ask a similar question, why Moses wrote about himself in the third person and not "and G-d spoke to me..." but it is a different question.