i think you are seriously misunderstanding how tough animals are, historically humans hunt in packs because even with massive specialized spears such as boar spears theres a very low chance of 1 hitting an animal
vintage story could definitely use a future trait system, locational damage and improved combat system to make more forms of hunting viable but that same system would most likely increase the danger levels through damage the animals could do to you, bleeding, broken limbs, problems like that
i think the core issue here though is your understanding of weapon(javelin) damage and animal resilience, something like a javelin wont usually one hit a person, and definitely not a deer, to be a confirmed kill in one shot you might need a ballista
you would need to throw a whole bag of javelins to get to the level of lethality of being hit by a modern car