Iguana,
It's a different thing to survive for a week in the tropics on only fruits, than to survive and thrive year-round, year after year, in the much harsher climates of this Earth. And I wonder how many of those 50 different edible fruits were as sweet as a regular domesticated overripe plaintain or banana or grape or apple or mango. Probably none of them.
Also, humans are not tree-dwellers. There's a reason we walk up straight and why our legs are 10 times as strong as our arms, whereas other apes who spend a significant amount of time up in the trees walk mostly on all fours and have arms almost as strong as their legs. We left the jungles and forests long before ever becoming humans, and opted instead mostly for the plains, savannah, tundra and other mostly open field areas where large grass and shrub eating game was available for hunting. Yes we can still do ok in the jungle and in the forest, but the main staple of our diet has mostly been meat. We did destroy some of the forests and jungles, but to believe that the whole Earth (or our natural living environment) consisted largely of these, is simply mistaken. The reason we destroyed what forests and jungles we did is because we don't thrive in those environments, whether as farmers or as hunter-gatherers.