You can call a player a wing or a small forward or a shooting guard, whatever you want, but players have a natural position (nearly always) and players can also generally play more than one position, usually something "adjacent" to their natural position. For example, PF is adjacent to C and also to SF. A player can be a natural PF but also be fine at C but not so much at SF. A different PF may be OK at SF but not so much at C.
If a player doesn't have a natural position, sometimes that is good, it just means they are more versatile, other times it is not good as it indicates that the player is a "tweener", meaning not quite a SF and not quite a PF (for example). The term "combo guard" has come to mean a player who is not quite a PG and not quite a SG, but there is no negative connotation. There isn't necessarily a right answer for any given player. I generally just watch the players on the court and label them based on what I see.
I like to narrow it down to ball handlers (or guards), wings, bigs. That is fine, but really, a wing can be more of a guard wing or a forward wing. They really aren't the same things. Bigs can lean more PF or more C, again, really not the same thing. Then there is the idea of the traditional PG vs the Combo Guard playing as a PG. The Celtics have not had a traditional PG in some time. I don't think even Pritchard a traditional PG. Smart, Brogdon, White, Holiday, all combo guards who can play PG, in my view. I probably need to see more of Banton but he looks like a combo guard to me so far.
Then we have a bunch of wings, Tatum, Brown, Brissett, Hauser, Stevens, Walsh (probably), and Mykhailiuk. I am fine calling all of these wings but some are more guard wings and some are more forward wings. Mykhailiuk for example may be able to play as the PG/Combo Guard/Ball Handler in a pinch but he is never going to be played as a big. Brissett on the other hand may be asked to play some PF in smaller line ups (not likely to be asked to play guard), but I still see him as a wing.
So I think this debate is about what is each players natural position or best position, but of course, nearly every player can play and will likely be asked to play, more than one role through the course of a game or season. Especially bench players, versatility is a great thing in a bench player. The more players that you have on the court that are at their best or natural position, the better the team is gong to be.