Sixth grade here. Too complex and too foreign for first-graders. Most of them are very concrete thinkers at that age and anything they say about how a civilization evolves will be mere parroting.
Exactly. First grade is the Grammar Stage in classical learning, and rote memorization is what should be done during this stage. Like I said, first graders learning that the Code of Hammurabi exists as an important event in history is appropriate. Asking First graders to understand why it exists and to extrapolate the meaning behind the Code would be too abstract for them. That’s why I said it depends on how the information is presented :)