I think they were both spiritually and mentally immature. After all, what do children commonly do? Name things with their own words. That's the job God gave Adam. After that Adam complained he had no helper, not realizing that God was there for him. Instead, he wanted someone more "like him," reminiscent of a "playmate." Further, if they were already jam packed full of knowledge, they wouldn't have even needed the Tree of Knowledge. It all points to immaturity.
And that is a good point about temptation, Asteriktos. We have to be given the choice, or we have no choice.