Edit: apparently this is a very common form of Japanese storytelling called an isekai. There are 8 billion people in this world, no idea can be original. And sometimes you miss out on things many other people know. I’m clearly one of today’s lucky 10000.
Finding a weapon is definitely the highest priority. As soon as everyone starts freaking out they’re coming after anyone who has something they want. After the bloodbath you can use your weapon to get food or possibly help with making shelter, and you’ll be ready to meet the natives once they arrive – just in case they’re not friendly and are at a lower technological level than what you have available.
Most cultures don’t immediately leap to “better kill everyone else in the train so I can take their stuff.”
Some don’t, I’m not sure about “most”. Regardless, I’m not waiting around to see what kind of passengers I’m traveling with. If everybody plays nice and works together then that’s great, we all have a better chance for survival. You still need to protect yourself against any hostile natives or wildlife because everything you know about what’s safe and what’s dangerous just went out the window.