Learn English – Some questions about these two sentences: What did I have and What have I

The question is broad and depending on the context, the meaning of those sentences drastically change. Since the question is broad, I'll answer that way.

Both the sentences broadly mean the same - you (at some point in time) were present at that place. However, a subtle difference is...

I was there - merely talks about the past event that you were present at that place.
I have been there - talks about the past event of you being there but also emphasize that that event has something to do in the present talk/scenario. The current scenario/talk could be the result of you being there.

In these sentences the two verbs are completely interchangeable. There is no significant difference.

Elsewhere there would be differences, of course. Animate objects tend to grow and inanimate objects tend to expand, for instance. Even in those usages there are often cases where the two verbs could be swapped.