Questions
* What happened at the ending, like why did Bigfoot didn't kill Bryan?
* this question might be unrelated, but is Bigfoot real or is it all stories?
1) No it did not kill him. It was motivated by revenge for its relative that was hit by the car at the start of the film. When the last guy left broke down in front of the Bigfoot and seemed genuinely sorry, the Bigfoot seemed to realize that and forgave him.
2) Most likely not real. I really enjoy reading Bigfoot stuff and watching documentaries about it, but I highly doubt Bigfoot actually exists. For a species like that to exist in the wild there has to be a decently large population, and there just isnt the evidence to support that.