A Kamehameha is invented by a turtle hermit named Master Roshi a 300 year old man tought Goku (Kakarot) this techqinece but it took Roshi 50 years to master it and Kakarot (Goku) learned it in 1 minute. A Concetrated Kamehameha is learned by a Saiyan (Humans) martial artist at lvl. 16 when a spritualists is learned a Super Kamehameha in the beginning. Grandpa Gohan can use a Kamehameha as well.
it is noticably used as a common technique used by Goku throughout the tv series.