Replacing human labor does not equate to replacing humans.
I’m arguing that humans will always need other humans. And for that reason, there’s always need for human work. This is sort of “Gödel’s incompleteness theorem”; that new innovations always yield new work tasks, job positions, and stuff for people to do.
I’m basing this on historical precedence: during industrialization (starting from ~1760), human labor was HEAVILY replaced by machinery. Later, new industries and job roles started to emerge, especially in the service sector (starting from ~1950s).
In agriculture, much of human/animal labor was replaced by machines (yet people are still needed). In manufacturing, much of human labor was replaced by machines (yet people are still needed). In services, much of human labor was replaced by machines (yet people are still needed).
How does this dynamic work? In at least two ways:
(a) New technologies create new industries that require new job roles.
(b) New affordances create new needs that require new services that create new job roles.
A major advantage of humans is that they are “flexible”; they adapt to new circumstances. Both on demand and supply side of the markets. So, young people just need to stay optimistic and energetic, trying to learn the new skills required to be competitive in today’s job market. Instead of listening to the “we will all be redundant in the future” laments.
(From a scholarly perspective, there’s also a chicken-and-egg dilemma in that “do new needs create new services” or “do new services create new needs” but either way, new job roles are required.)