the spider is pretty easy; even if you fight her legitimately. you have upto 4 characters, how is 138 hp too much? the minotaurs after her are stronger, as they can send you flying off a ledge, leap on you, while you're prone, hit you again(not complaining it was fun).
I beat her by sneaking and shoving her into the underdark. insta death because of huge fall damage.
I beat the minotaurs by sneaking, shoot and hide again. They just stand there and wait to be killed. I entered underdark through the temple.
If you compare some (not all) enemies to the PnP version, in BG3 they have much more HP.
Thats why I said: Stick closer to the PnP rules, remove some changes to rules (dipping with candles, many things that give advantage in BG3 but not in PnP, and so on) and make some enemies a bit weaker in return.
It is possible to win all fights in the game and if you know how to cheese the hell out of the game its very easy, like rest spamming, barrel mania and enemies who don´t do anything if you attack from stealth.
There will be higher difficulty settings with no reload option later. We can only play on normal now and I think this should be relatively close to PnP.