“Since their life spans would have been perhaps about 30 to 35 years they simply had no time to learn stone masonry, stone carving nor building large megalithic structures.”
Huh, that is right in the range for Mayans, Incas, Aztec (maybe shorter for them). They built complex large stone structures, carving, etc. etc.
You should get along well with SunkenCiv above; you cannot perceive the irony in my statements.