Minsc was originally a table top character, like most of the BG1 companions.
![[Linked Image from upload.wikimedia.org]](https://upload.wikimedia.org/wikipedia/commons/thumb/0/05/Minsc_Character_Sheet_from_Cameron_Tofer_pen%26paper_game.jpg/1200px-Minsc_Character_Sheet_from_Cameron_Tofer_pen%26paper_game.jpg)
The character sheet was printed in 1989, so the character was probably made not too long after, if not that year. This was before barbarian was introduced as a fighter kit in 94 and as a full class in 95.
That’s why he is a berserker ranger instead of just a barbarian. Barbarian feels much more appropriate to his nature, especially in 5E, where rangers can do much more spell casting.