>>4 >>5 Esperanto is a fail attempt to make a constructed language looks natural by stealing everything in a few languages. Toki pona is even worst by stealing a lot less.
Now, since man can write and/or since manipulator who have interest in manipulating language exists, all languages became progressively unnatural, so, there's no more such things as a "natural" language.
Some might argue that nature is a human construction, well, it's a word and a concept behind that word invented by human, but what it describes exist anyway (whether it is considered as important by the interlocutor or not).