Have you lowered the game difficulty, unless it is already on easy? Once you get through the temple you can put it back.
Stay on the blood trail to avoid being poisoned.
Before the raft section you have to jump across, just stand and wait for your health to recover (you should be able to move out of the way of the path of the fireballs from the walls, without getting into the poisoned area). I was a high enough level when I went to the bandit camp I could stop and quickly loot the bodies on the raft, but obviously you would want to keep running when you land and jump again to get straight through as fast as possible.
Once you get across you should either be able to land out of range or move so Jargon doesn't have a line of sight to shoot arrows at you. I don't recall having to deal with him right away, but I had my creature summoned (to help clear the skeletons), who may have chased him back to where he stands opposite the exit door.
If you are playing a warrior, you should do better against him if you Rush Attack and at least get him switched to melee combat. If you are lucky the Rush Attack will knock him down briefly, allowing you to get an extra attack in, or use a potion.
Do you have an earlier save inside the temple? If lack of potions is a problem, then just redoing the beginning may help you conserve more for later (I did much better staying on the trail the second time than I did the first).
Are you using your creature (if you have it) or a summon? Do you have a spare skill point you could use (after saving) to try out the ghost / demon summons, or Fireball, or something?
