The Qur'aan is indeed Perfect. We are not, therefore we will inevitably struggle to grasp its True Meaning.
Those two statements are anything but established truths.
They are articles of faith that each person must feel free to accept or reject however they please.
If for no other reason, because the lack of such freedom would mean that they are in reality misguided.
Frankly, the very frequency with which I am invited to accept them at face values hints very strongly indeed that they are false.
Nothing that I have ever read of it, about it, or from anyone ever gives me a reason to doubt that assumption. I do not expect that to happen, either. And that is ok.
If anything, I feel sorry that so many people (mostly but not always Muslims) seem to feel so bothered by the simple, unimportant fact that not everyone is meant to be a believer in God nor in the Quran. Such a situation often puts us in a difficult situation, having to choose between lying to people or hurting their feelings.
Moreover, it was revealed in a particular context, a particular time and place, in accordance with the needs of its audience. God did not need to spell everything out because His audience was very familiar with those things and would have straightaway known what He was talking about. We live in a different time and/or place, so some things are not so clear to us. This is why we need the Ahaadeeth to help to guide us. And why we must talk to other people, hear their interpretations and consider them. And of course ultimately, and constantly, ask God for guidance.
If that works for you, that is great. I feel uneasy with the fear that you might expect it to somehow apply for everyone, though.
That is a challenge that Christians, Muslims and Bahais often present me. They tend to mean very well, even while holding entirely unreasonable and abusive expectations. Not everyone can or should be assumed monotheistic or converted into one.