Can we use the same introduction text while promoting our hubs on different promotion platforms?

Well, whatever the case maybe there is no copyright infringement if that is what you are worried about.

It depends on the amount of text being quoted. If repeating a few paragraphs or more, that may cause the material to be seen as duplicate content. Better write an original introduction.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.