Why should you believe in a book written, in part at least, by a “human handâ€??
I agree with you completely: if the written Torah is even partly of human origin then we are not doing ourselves any service by believing. A book that claims to have been written entirely by Moses �taking dictation� from G-d (see Deut. 31; 24), but which was instead a compilation containing human observations and agendas is a fraud and has no place on my shelf.
The Torah ONLY has value of any sort (beyond the poetic) if it’s exactly what it clearly claims to be: Divine.
I believe that serious evidence exists to support the Torah’s claim of Divinity. Either way, though, a thinking Jew has to face the question that you’ve asked. If you’re interested, there’s an online book that does an excellent job addressing the matter directly. This evidence can also, for many people, be a strong first step to faith.
Wishing you all the best,
Rabbi Boruch Clinton