Yeah First Blood is actually a very different film, hell he only kills one person in it and you could almost say that was accidental (ish. From my recollection I'd argue Rambo wasn't trying to kill, just force the chopper to veer off)
He was softened for the movie. In the novel he kills the whole damn police department plus a buttload of other people. The town is also pretty goddamn flat by the last page of the book.