The opposite of knowledge worker would be an unskilled laborer.

Investopedia defines it:

A segment of the work force associated with a low skill level or a limited economic value for the work performed (human capital). Unskilled labor is generally characterized by low education levels and small wages. Work that requires no specific education or experience is often available to workers who fall into the unskilled labor force.

The opposite of knowledge worker would be an unskilled laborer.

Investopedia defines it:

A segment of the work force associated with a low skill level or a limited economic value for the work performed (human capital). Unskilled labor is generally characterized by low education levels and small wages. Work that requires no specific education or experience is often available to workers who fall into the unskilled labor force.

In the context of labor, skill, according to wikipedia, means:

a measure of the amount of worker's expertise, specialization, wages, and supervisory capacity.

In a continuous view of the workforce, knowledge workers would be at one end, and unskilled laborers would be at the other end.

The opposite of knowledge worker would be an unskilled laborer.

The opposite of knowledge worker would be an unskilled laborer.

Investopedia defines it:

A segment of the work force associated with a low skill level or a limited economic value for the work performed (human capital). Unskilled labor is generally characterized by low education levels and small wages. Work that requires no specific education or experience is often available to workers who fall into the unskilled labor force.