Child Anakin from Episode I was actually super peppy and optimistic, had plenty of friends despite being a slave, and enjoyed adventuring away from Tatooine with new people in new environments. Note that this was all before his Jedi training.

It’s not really obvious why this animated child would turn into the epitome of angst by Episode II, except that Master Windu may have been right in saying Anakin was already too old to become a Jedi, and so he wasn’t able to adapt to their rigorous social rules since he wasn’t raised into them from infancy like other Jedi. In a way, the Jedi doomed themselves by breaking their own code on age restrictions.