Europeans didn't really get to most of the more isolated inland areas in the Americas until the 1600s or well after that, though.
It takes more than a few decades for things to regrow. There's a reason that half of all towns in New England have the name "field" in them. The impenetrable thicket that characterizes unmaintained New England land would have been foreign to literally every human to ever set foot there prior to the mid 1700s (decades of re-growth after the natives had been mostly driven off but not long enough for complete cultivation by europeans).
Now, obviously that's not that far inland, but by the time you're talking about the french surveying the continental interior native populations had stabilized. The worst disease epidemics were very much at 1500s and early 1600s thing.
Have you ever seen a cleared lot that hasn’t been touched for a decade? We have a few near my house, and it is fascinating how wild they have gotten in such a short time.
Multiplied 10x and set in the rainforest, I would expect signs of humanity to be completely hidden.
They mostly gave all the waterways colloquial names based on the Indians and of course that got copy-pasta'd onto all sorts of charts and maps so the government couldn't redefine those even if they wanted to.
Most of the rest of the country (including the mid Atlantic despite being settled at the same time) was far more deliberately surveyed and named.
Of course probably it took quite a bit more for it to reach the Amazon but it's not like Europeans were that familiar or explore the region that much until the 1800s or so.