Growing up as a young boy, I and my friends often pretended to be one of an array of archetypes: warrior, cop, robber, cowboy, Indian, knight, spaceman, etc. Similarly, young girls pretended to be princesses, fairies, mermaids, etc.
What archetypes, if any, did children pretend to be in Medieval Europe?
Warrior was a huge one back then.
Toy soldiers like this were common: http://ak1.polyvoreimg.com/cgi/img-thing/size/l/tid/20044452.jpg
Detail and and quality of these types of pieces vary greatly.
Toy weapons were also extremely common and play with them was encouraged as it was a way for children to become familiar with various weapons before they could start training with the real thing.
This is a great academic article about the toys found in an archaeological dig in the 15th century Norwegian city of Bergen: http://www.academia.edu/1842567/Beyond_fragments_and_shards._Children_in_medieval_Bergen
It must be noted that the closest thing to professional sports the average child in Medieval Europe was likely to witness was combat tournaments. Jousts, duels, team melees, archery competitions, etc... The champions from these tournaments would have been (locally at least) akin to the top tier NBA and NFL players that are often seen by children today as role models.
