I have had very few deja vu's, but seemed to have more the first year I was a Christian. I don't know why, other than the explanation you gave -- that God was showing me there was more to life than what I saw in front of me. A supernatural realm.
While prophecy makes sense to me, deja vu's don't. They are like folds in time. I believe that God can see all variables and how they could play out in the future, but we still make choices that redirect our paths. Sometimes bad choices. So it's confusing that a scene, another person, a timing... could all be predicted.
We also see that on those angel reports on TV. Children seeing things that later prevent an accident.
God tells us things in advance when He sees we might suffer from dangers. We can pray, prepare, act wisely, and understand a situation better when we face it.
In God's way of doing things, giftings are meant to be used and shared with each other. When we give from what we have -- whether insights or talents or resources, we all benefit. Sometimes God will give one person a message for another, to reinforce and confirm.
In the parable of the talents (currency), the servants had choices in what they did with them. Hoarding and protecting -- keeping what God gives you for yourself -- leads to stagnancy. Allowing it fluidity and life and movement will benefit you, the giver, and other people.
I have to confess that I am not always open with the messages God gives me -- sometimes out of discretion, sometimes because the message does not seem to apply to other people. But the point is, move in love. See how God gives, and continue that generosity outward, with messages He has given you.