a lot of the intrigue is eventually going to go away once he wins the battle for the kingdom, but there is going to be alot of new witches soon and everybody in this serie is important to some regard.
Also we are still really far off, getting to be crowned king of greycastle is pretty much just the first 1/5 of the story, so there is still a LOOOOOOOOOONG way to go.....
even some of the "nobody" foot soldiers are eventually going to play an important part in the story, not just the once we have seen so far.
( one of my personal favourite "nobody character " is a PTSD warhero sniper who goes mental after his squad dies and then he becomes sniper rambo who thinks his one of his dead team members is haunting him to help him out He wont show up until the the MC is king and starts fighting the church sometime in the next arc, so there is still awhile untill he becomes demented rambo )
So yeah there is a ton of character who you should remember who they are to the point it gets hard to keep track of everybody.
Also the light novel is amazing, but its so detailed that its super slow to read.