Question about the Rambam's year

Hello Rabbi Michael
 
I wanted to ask about the Mishnah of Maimonides (the teacher of the perplexed and part of the Mishnah of the Torah) and perhaps in general about the relationship between the opinions and personal understandings of the first sages and those before them – to what extent are their words valid as the words of the living God?
That is, I read Maimonides' opinion on the survival of the soul of every worker and other things, talking about different things in matters of spirituality, and the things are puzzling and completely far from what I learned in my books Musar, Gemara Mishnah, etc.
And so are the words of the Kabbalists, Zohar, some of the legends of the Sages, many things are unacceptable to me. On the other hand, those books have a strong audience of believers who see them as the very words of the living God!!! And I am confused as to who to listen to?
How binding is this? Are these purely personal opinions and understandings? (After all, Rambam is not a prophet.) How much room for maneuver do I have in what to believe and what not to believe according to the rules of our Torah?