Sword in the Stone is a great example of a relatable hero. He is just a normal kid until the sword in the stone chooses him to become the next King. How more relatable can kids get to another normal kid?
I remember as a child being legitimately jealous of all the books Merlin had. I can neither confirm nor deny that I'm still jealous as an adult. Damn wizard doesn't even need to assemble an IKEA book case.