I fully agree with all what you said, except the speed of growth for the most beautiful, largest, canopy-making trees is definitely less than man's lifespan. And also: "vast and mostly untouched". Did you go in field? I know (from my own experience) that most of "untouched rainforests" that we see using Google Earth, aren't forests anymore! I told this in "Giant deforestation"- thread already. Here I just "copy and paste" what was said there:
...By the way, you know - so many places on Earth look like forests, but aren't forests at all. One instance, as I said above: high speed of destruction... Some areas were cleared off trees just few months ago, so these deserted places aren't shown - simply because the Google team cannot update all images as fast as greedy folks destroy the Earth.

There is also another "trick" about forest images... I thought I see good tropical forests in some places until I actually went there (in field) myself and discovered that these are in fact huge plantations of commercial trees and brushwoods instead of forests. Expensive experience! Some of my "adventurous trips" thus became a mere waste of time... (Well, at least I warn you now).

For example, rubber tree plantations in Indonesia. They can look very similar to a rainforest (from space). Coffee, cacao, and other plantations in tropics are often made under several remaining tree canopy. As result, from space it is impossible to understand what is seen below... You plan a trip, thinking you gonna meet orangutans, gibbons, hornbills, orchids, rafflesia, forest peoples, and all other inhabitants of a typical Paradise etc., but - instead - meet kilometers of boring plantations, where of course almost nobody can live, except for "modern people", who's basic activities are working/eating/TV-watching.
- Alex