Many megalithic civilizations around the world have Myths or Legends about Giants coming across the ocean to teach them farming and civilization

 So, it's not just one it is in Indonesia, Turkey, The U.S., Malta, and maybe even in the Bahamas regarding ancient civilizations too.
I would like to share an experience I had when I went to Nepal and India. Most people there (not all) generally are between about 4 foot 10 or 11 inches tall to around 5 foot 6 to 5 foot 8 inches tall. So, to most people in Asia I encountered especially in India and Nepal people often thought of me as a giant becuase I'm almost 6 foot 5 inches tall and at that time I wore size 14 Vasques cascade Mountain climbing boots most of the time then or I wore sandals in Thailand or other really humid hot places I went to in India or on the Terai (near India) of Nepal where there is the Chitwan National Park around 1985 and 1986 when my family and I were in Thailand, India, Nepal and Japan for around 4 or 5 months then the 5 of us.

So, what I'm saying is even me from America with mainly Swiss and Scottish heritage was thought of as a giant by people in India and Nepal and Thailand mostly but especially India and Nepal especially out in the country or in the Himalayan Mountain range up to 10,000 feet elevation where my family trekked then.

The point being that someone from  another culture might seem like a giant if those people didn't drink milk from domesticated Goats and Cows from which the growth hormone has affected the heights of people in that group. For example, the Watusi in Africa are all tall from drinking cows milk and blood of the cow for thousands of years. My Swiss ancestors drank goat and cow milk for likely thousands of years too along with Germanic and Nordic people. Why?

Because often in the winter time milk was all there was to eat because goats and cows would forage in the snows for blades of grass. So, if you couldn't drink milk for any reason often you starved to death then.

So, calling people giants often just means those people drank goat and cow milk for thousands of years and that's all really. 

So, the fact that giants came and taught people civilization makes sense in this sense when these myths from various ancient cultures all seem to agree about this before most of mankind moved from hunter gatherers to farming and raising herds of goats and Cows for milk and eventually cheeses of all kinds now.