That your brain training on all the inputs it sees and creating output is fundamentally more legitimate than a computer doing the same thing.

Copyright isn't some axiom, but to quote wikipedia: "Copyright laws allow products of creative human activities, such as literary and artistic production, to be preferentially exploited and thus incentivized."

It's a tool to incentivse human creative expression.

Thus it's entirely sensible to consider and treat the output from computers and humans differently.

Especially when you consider large differences between computers and humans, such as how trivial it is to create perfect duplicates of computer training.