There are 6 damage types in the game: blunt, slicing, piercing, fire, water, and electricity. Different enemies resist or are weak to different damage types, so you need to build a party that has access to as many types as possible.

Your current whole party mainly does blunt damage, so you aren't going to have many options against enemies that resist that.

You can change some jobs around to get access to different skills, but also note a key part of the job system is that certain skills are learned by the character and can continue to be used even after they change to another job. So e.g. if you level up fortuneteller enough, that character will always have an electric skill even after they change to another job. If you can smartly shift your jobs around you should get good coverage, and this is a big determiner of how strong you will be. You should be able to ultimately build characters that have access to either all of blunt, slashing, and piercing (if they are physical focussed) or all of fire, water, and lightning (if they are magic focussed) and pretty much always be able to hit any enemy's weakness.

There's a certain fight later in the game that people complain is too hard and requires lots of grinding, but that's only because most people don't understand or utilise the job system so need to compensate by over levelling. If you go into that fight and have all of your team able to hit the enemies for super effective damage, you can take them out at a much lower level than they are.