Yes I know that but can I still play an old save from a previous Keep creation without an online connection or not?
I don't fully understand your question. Every time you make a new save for Inquisition, if you want to import a Keep world state you DO need to connect the the internet, yes.
Here is a scenario: In the Keep you make 5 different world states. Then you load up DAI and make 5 new characters, each with a different world state from the Keep. Then you go offline. You can switch between those DAI saves all you like because those choices are "baked in" to your DAI save.
Another scenario: Let's say you're having a problem because the Keep is too restrictive with the number of world states it allows (final number not yet determined). If you have World State Alpha and you use it on DAI Save Alpha, you can go back to the Keep and change some of those World State Alpha choices and they will NOT affect your DAI Save Alpha. You can then use that altered world state to create DAI Save Beta. But to do all of these changes, imports, and so on you do need to connect to the internet.
Once you have your Keep world state all set and your DAI save all set you can then go offline and play.