I would say the abacus is the world’s first computer. The Inca rope system may be the first computer in the America’s.
A computer is a device that allows you to calculate efficiently. It can come in many forms.
I’m 82. We had a giant abacas in kindergarten. I started school at age 4 yrs 7 months.
Tying and untying knots doesn’t rate really high on the efficiency scale. Nor does that shout out precision. (Have you ever tried to place a knot in a particular position along a string?) The most that this was was a record keeper, not a computer. My guess.