Not bad. For the first time I've given you a rep-point, for at least a momentary glimpse of light.
I think this is wrong. To contrast it with religion: religion is a belief system, spirituality isn't. Spirituality is more a stance one takes to what one thinks reality is. Therefore one finds spirituality in all kinds of world views: theistic (e.g. mysticism in Christianity or Islam) , non-theistic (e.g. in Buddhism), and yes, even in scientific world views.
So this is very wrong:
First, 'concepts' cannot be demonstrated. At most concepts can turn up to be useful to describe nature. Second, spirituality, as described above, is a description of the kind of relation you strive for to what you think is real, be it God, ultimate reality, or life just as you experience it.
Not in any meaningful sense.
Spirituality does not explain reality. It strives for, as your first statement says, to feel the connection with what one supposes to be real.
Yes, feeling connected gives a feeling of meaning. That is in my opinion one of the main motivations behind spirituality.
And no, it does not explain anything, so it is a category error to compare it with scientific evidence.
Now you are mixing up spirituality with intuition.
Nobody knows. You must realise that we evolved from previous natural species that could not talk, and so definitely had very different minds than we have now. By using language to literally describe things in nature did not arise from one moment to the other. So I assume originally religion and spirituality were not invented by people, but slowly emerged from more primitive forms of consciousness.