Victories and Doubts

Did you ever think about the fact:

David slew Goliath in the Valley of Elah when he was around 12 years old? One of the most significant victories ever for Israel since the whole Philistine army was outfitted with the newest and most highly protected technnology of their time:The technology of iron. They all had suits of armor, swords, shields and spears. The nation of Israel had two suits of armor and two swords, a lot of shepherds' staffs and a twelve year old who believed in God.

That Goliath stood about 9 feet tall, weighed around 400 lbs (a doctor told me that would be a reasonable weight for a man that size), and whose armor weighed as much as David did (125 lbs)?

That only a short time later David was hiding from King Saul, whose nation he had saved, in the Cave of Adullam in the very same valley he had killed Goliath?