These are very confusing and have a long history with Rowe/Brace/Paulson/Elder.
I actually do believe there are some of these generic postcard backs that are genuine period postcards as early back as the 50s. Issued by teams themselves.
Straight up to start, any player pre 1930 (even pre 1940 but there are probably some exceptions of players who had long careers and possibly had legitimate team issues in the 50s with this generic back) is a "reprint" and not at all vintage. If you see a random common player from the 1920s you collect, and it has this generic Kodak back, sure you can buy it but just know it was made to sell in the 1970s-1990s.
If your goal is to only collect original period items (I'm talking the photo used matches the same year, or a few years give or take of production) then your guy better be old looking or a player from the 1970s-90s. Or you know and have researched it is a team issue release.
I collect Red Schoendienst, here is an example of a Postcard from 1958 that was printed and given out by the braves in 1958. The only thing I can notice is the separation line under the word card is slightly to the left of the D, while on later backs it seems to be slightly beyond the D to the right. Also there is no border. I am not sure if those are full proof ways to tell though. But if I had to guess they are.
Real from 1958
https://www.ebay.com/itm/12576345340...mis&media=COPY
(And yes I just bought it, have been needing to for a while lol)