Hey, I don't have the whole context of this discussion but at the point of this comment specifically it's more semantics than anything else. Yes, anima is an ability one may have. Not a position like the "normal" 5 (fisherman, scout, SB, LB, WC) because it's something you can or can't do, not something you are good or bad at. A fisherman may be horrible with spears, but he can throw spears, he can act as a SB just as he can act as any other position (of the "normal" 5). A non-Anima can't ever control Shinheuh (forget oddities like Baam, who was able to use Arie swordsmanship when Albeda was inside him or whatever, that sounds strange). In that sense, it's probably the case (SIU could always change later, but as of now it seems to be this way) that every Anima gets a "normal"/traditional position of the 5 at the Floor of Tests regardless if they eventually fight using those abilities or not.
The question about primary combat ability or who/what an Anima is is just semantics. If by primary combat ability you mean all Animas were assigned a normal position and are able to fight (despite how good or bad) at that position or really any of the 5, then sure. If by primary combat ability one means the fighting styles and techniques a Regular/Ranker adopts, then surely one can go from showing it one time as a "I'm capable of doing that too" (YHS vs Ren) or don't seem to use in combat (Yasratcha and his cat) to fighting almost exclusively like that (Kendrick Diel, Dokoko, et cetera) i.e. their primary combat ability may or may not be Anima abilities, with most Regulars/Rankers that were specifically said to be an Anima fighting predominantly with the aid or exclusively with their Animas. Nobody says "YHS, Anima user", or "YHS, WC and Anima", or "be careful, that YHS dude is an Anima" but it may happen that a character is stated specifically to be an Anima and his normal position is not even mentioned. Of course that was just an example and most people probably don't know that YHS has anima abilities, but I think ppl can understand that.
Who/what is an Anima seems to just be a case of using the same word for two different purposes (like I said, semantics). Anima is both used to refer to someone with the ability to control Shinheuh, regardless of their proficiency at it (YHS is an anima, that regular little girl from 2F is an Anima) as well as to denote people with great Anima abilities ("LPB FH is said to be the greatest Anima of the Tower") or that at least use it as a significant part of their skillset.
Also, kinda related to this topic, idk if Traum "is a SB". Since he's a gifted Irregular he'll probably be better at it than most SBs, but that doesn't mean it's the way he physically engages opponents when fighting seriously, I wouldn't jump the gun that fast. Remember the context, he wanted to kill Nennen, and for storytelling and visual purposes he couldn't just obliterate her body or something like that, it had to be visually impactful but not humiliating, he was showing piety to a creature not even worthy of domination. In what ways he could achieve that? Surely not with some LB bs skill/ability. Also not with needles/hooks/fisherman abilities, he wouldn't move up to her or use something so huge that he wouldn't have to approximate, it'd be disproportional. The same goes for scout things. Not using a shinheuh, since any of his giant shinheuhs would be overkill, and summoning a small, fodder shinheuh just for that when he already has a giant shinheuh deployed would be... contrived, less impactul, and less personal than killing her with his own hands. He could just blast a whatever Shinsu technique or just use a sufficiently powerful baang, but it wouldn't be visually impactul, could destroy her body and would leave room for doubt as to how and what killed her. That leaves a simple spear as the best way SIU could show it to us and in universe, when Traum appeared with Nennen at the Canine camp WW didn't ask himself or Traum what happened, who killed her, he knows it was Traumerei and that he did it simply and direct, without any hesitation, one hit kill, pierced her with a spear, the weapon still there, her blood dripping from the wound and mouth. A great scene, in my opinion, it makes good use of its medium strong points.