The truth is that we simply do not know. Since historians don't deal with 'what if' questions, we base what we know out of what actually happened. However, I do understand where you're trying to go with this question and I would recommend that you pick one historical figure that you've mentioned (or an event), and ask your questions surrounding it. Instead of asking if Hitler didn't exist, would the invasion of Poland have happened? Ask - what actually did happen? Follow the history rather than the hypothetical. :)