This lack of compatibility was exactly why I was initially unsure if I could enjoy the game. Rangers and Barbarians used to be a special kind of Warrior, so you had the extra strength column that other classes, capped at 18 for humans, didn't get. You can use books from across the TSR editions interchangeably with little or no adaptions, but Wizards changed the game and many narratives in such a way that a lot had to be "re-imagined" in distorted form. Luckily, I didn't play the earlier BG titles (yet?), so I met Jaheira, Minsc and Boo for the first time in BG3.
Yeah Minsc's original strength score translates to +2 to attack and +5 to damage so can't be immediately translated to a 5th ed score - but I'd give him 20. If nothing else for the crawling out of a mimic scene.
To get Minsc in BG3 working somewhat like he did in the originals, you need to multiclass him Barbarian/Fighter or even Barbarian/Ranger/Fighter. My last run I gave him 3/3/6 and it worked better than I expected. Since we can respec him it is no biggie, I just think it is unforgivably silly by Larian to introduce Minsc with a scene screaming "Whoa, this guy has superhuman strength!!1!" and then when he joins your party he has a score of 12...
