The Kenbak-1 is widely considered to be the world’s first “personal computer”. Designed and invented by John Blankenbaker of Kenbak Corporation in 1970, and was first sold in early 1971.
Blankenbaker notes one of his big mistakes was trying to sell into schools instead of to hobbyists (as Apple would later do). See PO Death
Others consider the Programma 101 to be the first personal computer, though the cost of that machine was significantly greater, and marketing was targeted at businesses.