I live in NE FL. I raise Key West chickens. I got my originals from a rescue group in 2011 that relocated the KW chickens straight from KW. The first several generations were very feral/wild and exhibited all those instincts for survival etc. At one time, I had hens escaping into woods, small groups getting way up into the Live Oaks to sleep etc. due to a neighbor dog trashing my chicken run one day.
We have way more predators around here than they do on Key West. We have hawks, eagles, owls, coyotes, foxes, racoon, possum, bobcat, cougar, lots
of feral cats, stray dogs, or people who let their dogs roam, etc.
None of those KW that escaped lived very long if they weren't caught. I had 9 chickens taken from trees in one night by owls. The hens nesting in woods might hatch out chicks but the chicks would get picked off by predators and then eventually the mothers. Luckily, I still have a good flock that didnt escape.
So I don't think any FL jungle fowl could live very long these days in the "wilds of Florida" with the exception of the keys or some other cut off area/ island etc. lol.
It seems like there would be more predators back in the old days than now so I dont know if any could be wild back then either. Chickens can fly well especially the small breeds like Key West but they seem to fly short distances. Anything heavier would have an even harder time.
Your heritage jungle chickens very well may have been from Spanish, Cuban, or even Puerto Rican game lines. Many of the Key West/Gypsy Chickens were originally brought over on trade ships or pirate ships from those countries. So the same ships were probably frequenting all of coastal Florida
They were brought over for meat, eggs, cock fighting/entertainment.
Here is an thread I wrote about Key West Chickens' background.
https://www.backyardchickens.com/threads/key-west-aka-gypsy-chickens-thread.441267/#post-5505356