Wasn't the Real Origin Point... (Spoiler Alert)
As the movie progresses it becomes clear that the people in the cabin are four generations of a family. Once we come to terms with that then we have to ask why they are there. They are there to change the course of history by changing the past, in this case stopping Hans (the oldest member) from dying. This is where things break down a bit because the person standing outside the safe is the blonde. If things are about getting her life on track then the timeline to alter is the one her mother dies in. That would mean calling an ambulance for her or stopping her husband from fighting in the war so the blonde does not grow up with spiteful grandparents and eventually run off with a Clyde to her Bonnie.
In the movie as is, stopping Hans from dying should result in the blonde and the guy never being born. I'm not 100% sure but I can't imagine tons of ex-Nazi soldiers were allowed to immigrate to the US after the war. Hans being alive means that Sam's mother probably never remarried, which is the event that went on to shape her meeting her husband. Yes she could have met him some other way but it is highly unlikely that Hans and her mother would have immigrated to the US to the same town as the original timeline and things would have played out the same way.
I liked the move but really wish some more thought would have gone into the shaping of the new timeline or at least more explanation would have occurred if I'm just not understanding things.