You're confusing the economic system under which something developed with the conditions necessary for its existence. Saying AI developed under capitalism doesn't establish that capitalism is necessary for AI.
Nobody claimed that labor, materials, or energy are free. Those are physical and organizational requirements, not capitalist requirements. Workers can be compensated without private ownership of the means of production.
Public institutions have funded AI research and constructed advanced computing infrastructure. Corporations aren't the only entities capable of organizing labor and resources.
Yes, the AI I currently use is corporate. That establishes who owns the service, not that the technology is inherently dependent on capitalism.
Your argument amounts to saying that because something hasn't happened under a particular alternative, it cannot happen. That's not evidence of impossibility. You're asserting necessity based on historical circumstance.