But if it WERE possible to time travel into the past, then I'd assume it wouldn't actually mess with our life, I'd think it would create another dimension or something that we mess with.
Almost like we took a huge essay on the world and everyone's life stories on a Google Doc, then we hit "make a copy" and then edit parts of it, but that copy doesn't effect the first one, you just made a new one, where everything is the same except whatever you changed, and then time travelling back would be even harder, but I don't think anything would really change.