بسم الله الرحمن الرحیم
According to the verse: (7:3) and (5:55) which states that; do not follow those things which are not based on Quran Karim, even if it is said that, it is from Allah (s.w.t) and the prophet (s.a.t.a.w.s). In the verse (28:50) it is said that; those they do not follow Quran Karim they actually follow their whims and desire. such people are the most aberrant. And Allah (s.w.t) do not guide oppressors.
Wa ma Alaina illal Balaghul mobine
That was an accidental like when I was about to click "reply with quote".
Our foundation should be based on that which is most truthful and less doubtful - reseaching objectively, truthfully, logically, and sincerely should bring a sane person to the conclusion that the Quran is the best foundation and the most worthy in terms of authority.
But then you will find that the Quran departs wisdom, guidance, admonishment, and some important laws, but wouldn't be much of a book readable by everyone if it was full of everything, since the pages would have been endless and some verses would have been irrelevant to some -depending on task, profession, situation etc so there is more need for stable guidance,
When you search for wisdom and guidance, and how best to interpret the Quran, you need to look at the life of the Messenger to whom it was sent.
This is when you'll need to look for genuine narrations from him, looking in the authentecated books such as those compiled by Imam al-Bukhari and Imam al-Muslim will fetch you some, they have been conveyed by people through generations a little further down the line and do sometimes contain errors and false attributions, but they are what they are, and they contain some of the most truthful narrations of the Messenger, and cannot be dismissed wholesale, then there are other books and wisdom scattered all over the planet - seek the best you can on the firmest and most truthful foundation.
I'm sure the Quran didn't tell your mother how to change your nappy, and that whoever gave her good, truthful, and sincere advice wasn't sinning in advising her. I don't think you would have bothered to read it if it had a few thousand chapters devoted to changing nappies and washing utensils, and making custard and apple pie and how to do high jumps either.
The Quran contains less text than the average book you will find at your local library (disregarding the children's section), and is readable by every individual who can read, there is no excuse for not reading it, but I am certain that you have read more than that.