If you copy a Itlimoc, Cradle of the Sun, you get an Itlimoc, Cradle of the Sun, not its front face. The most relevant rule from the Comprehensive Rules:
711.4b While a double-faced permanent’s back face is up, it has only the characteristics of its back face.
The further down in 711.5, the rules also acknowledge the possibility of copying the back face of a card:
Example: A Clone enters the battlefield as a copy of Wildblood Pack (the back face of a double-faced card). The Clone will be a copy of the Wildblood Pack. Because the Clone is itself not a double-faced card, it can’t transform.
See also rule 706 for more on copying.