So I’ve read maybe 1/3 of the answers so maybe I’ll repeat something already said but this is a bit too long for me to read everything 
First I’m not a casual gamer but I hate anything that has to do with hand/eye coordination and reflexes. I love old style RPG where your character stats and some RNG determine his abilities and not at all your own ability to time a hit etc, but I wanted to try this game anyway for all aspects outside of combat.
So I had the same issues than you with combat, because my henry might learn stuff but I’m still bad at fighting, I don’t have good reflexes and I tend to just freeze.
Anyway here are my 2 cents :
You cannot find the captain if he’s still in the stud farm and he won’t leave until you finish Ginger in a Pickle.
Good news is you can absolutely finish that quest without any fighting either with speech (I knew I wanted to avoid fighting as much as possible so I went high speech from the start) or just asking for help.
The game is done well enough that it knows you might be unable to fight your way out of a paper bag at that point if you went straight for the main quest before exploring a bit because you have no combat skills, low stats and no gear. So it made up for it by allowing you to go for help. Won’t say more to avoid spoiling everything in detail.
So you can complete the quest Ginger in a Pickle without fighting, or if you want to kill some bandits yourself well, they sleep at night, depending on your stealth skill and if you know how to assassinate someone (Perk) then you might go that route.
But after that’s done and until you get a decent level at your weapon of choice + decent stats + decent gear well forget fighting, just run from combat when you can , use stealth, diplomacy, bribes etc.
It’s not because you got a quest now that you have to or can tackle it just then, sometimes you have to come back ingame weeks later because you need preparations and training first.
I would say that with an, ok sword, a bit of protection (light armor) and somewhat around 5/7 in combat skills and maybe 5 to 10 in stats if you’ve unlocked perfect block and master strike with the captain you should be able to handle light armored foes 1 on 1 without too much trouble. Except if they’re soldiers of any kind, but bandits and the like should be at your level. If you find a group, run and try to ahve one of them follow you, kille that one and go kite another.
When you train with Bernard don’t get discouraged when he kicks your but he’s way too strong that’s normal he’s an elite fighter, he’s way above most of what you’ll be fighting out there so don’t worry.
And also specially at first forget about landing blows, learn to defend.
With a high enough defense and learning to block at the right time to trigger some master strikes often enough you can defeat many enemies without a problem, just patience. Bernard is great at teaching you defense. I was barely 8 in sword when I reached 18 in defense it was my first maxed combat skill, the only other skill I maxed before was herbalism.
Defense can help you a lot in combat because if you time a block well you don’t take any damage, that’s master block. But if you manage to time it perfectly then you automatically will land a retaliation blow that does a lot of damage to your opponent, that’s perfect strike. It takes practice to be able to time right but ot’s the easiest way i’ve found to fight.
Archery can also help you a lot but same than with the rest until you’re level 5 forget using your bow against anything but rabbits, after lvl 5 with a decent str/agi a decent bow you can maybe hurt one or 2 enemies a bit to weaken them before a fight but you still won’t be killing anyone even with a head-shot on an unprotected character.
But once you reach 7 you begin to be able to kill people even one shoot them if they’re in clothes or you shoot an unprotected part, around 10 you kill evne light armored enemies and at higher levels with good gear you can badly hurt even armored enemies.
But it takes time, practice and good stats/skills/gear.
Hope this will help you or other out, it’s not easy but it’s doable, I’m crap at it and I managed.
I still can barely land a blow where I want it to land even though my Henry has 20 sword 17 warfare 20 str and 17 agility, so I suck pretty bad. But he’s geared well enough that it doesn’t matter, I use defense/master strike that is automatic and doesn’t require me to do more than time my block and I do well in combat. It cost me around 5 hours of real time practice with Bernard to learn to time block and i don’t manage 100% of the time but I have gear that keeps me safe for when I fail. I at least perfect block most of the time and depending on the skill level of my opponent I manage to land quite a few master strikes and that’s enough to kill them in the end.
Tough if I can snipe them with a bow or use stealth I’ll.
