I'd take the argument to the physical level. Do we know how the brain works? To some degree, yes. Neural networks: nodes, weights and activation functions.

If one day we can map exactly an animal brain's architecture, how new ideas are learned etc. (is it backwards propagation or something else?) then we can replicate that behaviour using logic gates and floating point numbers.

Mapping a brain to a digital neural network architecture is such a prohibitively expensive problem I wouldn't know where to begin. Perhaps a biologist would have a better idea than a computer scientist. But it's enough to say that intelligence can theoretically exist on electronic circuits.