The headline literally says they lived in 3% of the forest area, which implies that the vast majority of the rest of the forest actually was untouched
10% of the Amazon soil is man-made terra preta.
The paper is just referring to this one civilization. It is definitely not the only Amazonian civilization.
not really, the 3pct was just what they scanned with lidars so far.
Perhaps, but was it untouched by design, or was it untouched because it wasn't economically feasible for them to exploit it?
Those two are very very different when it comes to assigning virtuous environmental brownie-points, and the latter is the default across most civilizations ever known.