You might have heard the sayings "Those who do not study history are doomed to repeat it." and "You can't know where you're going unless you know where you've been". Those statements are absolutely true.
If you look at history, many events from dozens, hundreds or even thousands of years ago have been repeated. The times/technology have changed, but human nature hasn't changed much. Many events today are very similar to events that happened before, and you can look at those and say "if we make similar choices today, these horrible things can end up happening later."