Do we humans maximize our importance because we are desperate to find a purpose to our lives? What is the GRAND reason for our being here?

Those are two different questions.

The first, actually two sentences, but all that in large, bold type, asks "Why?

The second is the by-line, which simply asks "How?". Mutations and adaptations are parts of the mechanics of the system, not the system itself.  

If you are really asking "Why?", I do not think anyone can answer - no scientist, no theologian, no philosopher.

 -  If you are not religious, it is easy but discomfiting to think there is no real point of our existence, nor indeed that of the entire Universe.

  -  If you are religious, i.e. you believe some deity is creating and operating the whole lot, it's all simply to suit that deity, whatever it might be and whatever its motives - qualities we obviously cannot know either. Equally discomfiting!

Ultimately though, neither answer is any more satisfactory than the Mediaeval European clerics who placed Man at the pinnacle of God's work, in a geocentric cosmos based on Ancient Greek ideas. Theirs was a result of genuine lack of knowledge, and just basic arrogance; and used to stifle curiosity in what is really out there.

The simple truth is that we cannot say WHY everything in Nature exists!  

  

I'd read the first two questions as you wrote them, in one sentence that offers a possible reason for what's it's asking. You've now added more!

So if you want me to divide it...


I am not sure if humanity does maximise its self-importance, at least not as much as it did in ages past when it thought itself the highest of God's works and could "tame" Nature to its own service. It still thinks that way sometimes but has generally realised that is no longer valid or sustainable.

A GRAND reason? Well, I leave that to theology, and even that cannot answer it. No-one can know WHY everything exists - just as the idea of our being some sort of experiment under way by some supernatural force, is unanswerable although I'd think it very far-fetched.

I do though agree with your general point about "working together for a common purpose", because I suppose without that mutual support, society could not work and life would be very unpleasant indeed.

I know biologists talk about "life cycles", a term pinched for anything and everything even where it is absurd, such as the "life cycle" of an inanimate, manufactured object. Philosophically I do not agree with the term anyway because any one organism is like the factory-made thing, in having a linear, not circular, life. The only things in them that live on for re-use are the chemical elements from which it is composed.  

No, we are not illusions; and I am not familiar with the Matrix story but I thought that was really about society being run by a computer it had built and programmed.

Your questions are valid; but not answerable because there is no tangible, valid evidence to support whatever you might suggest as answers. 

Happy Thursday!