The old terminology was one Center, two forwards, two guards. When one of the guards was designated as a point guard, the two and three became wings and the four and five posts. Today, almost no one uses that terminology; shooting guard and small forward are preferred.
I think it is more that everyone now recognizes that any terminology is suspect because the skills the players possess and the offenses teams run have expanded so much that trying to pigeonhole players into one of five distinct positions on the floor is meaningless for the majority of players. the old distinction of:
Center (5) - no handle, back to basket, incapable of hitting the backboard from greater than 7 feet. Unlikely to ever pass the ball.(Shack)
Power Forward (4) - shorter than a Center, with no handle, maybe able to hit the backboard from 10 feet. Only likely to score off rebounds which was their primary responsibility. (Paul Silas)
Small Forward (3) - can actual be counted on to dribble a few times and to occasional pass the ball to a teammate rather than out of bounds or to an opponent. Range from 7 - 18 feet and can hoist prayers from the arc. Afraid to go closer to the basket than 7 feet except on a break.
Shooting guard (2) - actually has a handle, but almost never passes the ball thinking they are always open and any shot taken from 15 feet out is a good shot. (really old school - centers and PFs would deck any guard that came within 10 feet of the basket every time until they learned not to attempt it.)
Point Guard (1) - can't hit the backboard from anywhere on the court except on the break, but loves dribbling and passing.
There were basic height ranges for the various positions as well.
As skills began to expand (and as offenses expanded to match the players' skills) 'wing' was used as a blend of Small Forward and Shooting Guard, Post was a blend of Center and Power Forward and Guard was a blend of the two Guard spots. Forward was a blend of the PF and SF skills. But those designations are still more limiting than the skills some players possess. At the same time there are still 'old school' players that are still quite easily designated into one of the five older designations.
The interesting thing is with the expansion of positional year end awards the basketball powers are trying to turn back time in the way we recognize player skills. There was already a debate with the Lieberman because it had become blurry as to who should be designated a PG. Now they are going to try to designate five specific positions and pigeonhole players that have much broader skills into a single position on the floor. Where do you put any one of Gabby, Napheesa, or Lou?
I find that people use any of the terms indiscriminately depending on the player being talked about or the offense being described. Fowles is a Center because she doesn't shoot from further than about 10 feet and is not likely to pass once she gets the ball near the basket. Sue is a PG because she prefers to pass most of the time. Charles is a post player because she has so much more range than a 'Center'. etc.