I don't know. Even Wellington lived off the land to a large extent.
But, with respect to the Incas, my understanding is that they didn't live off the land, but used organized supply depots. That works fine when you're suppressing rebellions or fighting civil wars or annexing the valley over the next ridge (often by intimidation), but it wouldn't translate well to amphibious invasions. And they were also used to having numerical advantage and not used to fighting people with more than a very limited range of tactics. I don't think an attempt to invade Central America, over not just a small stretch of water but several hundred miles of coast, would have gone well, nor was there reason to try it when there was always another little statelet just over the next ridge.
But, with respect to the Incas, my understanding is that they didn't live off the land, but used organized supply depots. That works fine when you're suppressing rebellions or fighting civil wars or annexing the valley over the next ridge (often by intimidation), but it wouldn't translate well to amphibious invasions. And they were also used to having numerical advantage and not used to fighting people with more than a very limited range of tactics. I don't think an attempt to invade Central America, over not just a small stretch of water but several hundred miles of coast, would have gone well, nor was there reason to try it when there was always another little statelet just over the next ridge.