the fact that the only "intelligence" that we know of is implemented in a massively parallel way should give you pause as to assuming that it can be done serially.

An optimization process (evolution) tried and succeeded at producing massively-parallel biological intelligence.

No optimization process has yet tried and failed to produce serial-processing based intelligence. Humans have been trying for very little time, and our serial computers may be barely fast enough, or may only become fast enough some years from now.

The fact the parallel intelligence could be created, is not evidence that other kinds of intelligence can't be created. Talking about "the only intelligence we know of" ignores the fact that no process ever tried to create a serial intelligence, and so of course none was created.

Unless of course the kind of AI that humans create is nothing like the human mind

That's quite possible.

The question is whether algorithms performing similar functions could be implemented serially. Why do you think that they can be?

All algorithms can be implemented on our Turing-complete computers. The questions is what algorithms we can successfully design.