I mean... Let's be real. This is the protagonist of a Metroidvania series we're talking about, so the parts you actually play out would obviously paint a decent picture of her, what with you having to solve environmental puzzles and all. At the same time, her lowlights really stand out. Sky stands out in the street smarts department about as much as Uncle Mimic stands out in the book smarts department... Rottytops knows just how to make Shantae look stupid (which apparently isn't too hard to do)... And Risky may as well be Senku Ishigami from Dr. Stone. But Shantae? Bolo... Can't say I'd trust him as anything more than a handyman.
Shantae? Well, her IQ is impossible to assess since her academic skills (which IQ only accounts for) are non-existent besides possible illiteracy. Granted it's just academic illiteracy since she can read simple signs, but I'm pretty sure it's still classist to mark anyone down for illiteracy. Does school exist in the Shantae world? I mean there were kids at Museum Town on a field trip. Her EQ should be pretty decent if she perceived Rottytops as her old human self, however.
Again, I will need to pull out Howard Gardner's Eight Intelligences as a simplification model: https://www.niu.edu/citl/resources/guides/instructional-guide/gardners-theory-of-multiple-intelligences.shtml
Her musical intelligence is the best aspect since she had shown to pick up dances quite quickly. I mean... Bellydancing is obvious, but I believe she picked up luau in Shantae and the Seven Sirens in Vera's hometown (I haven't played that game, so bear with me here). That should extend to high bodily-kinesthetic intelligence as well. Shantae's interpersonal intelligence should be exactly what you'd expect from an average person. Her intrapersonal intelligence? I mean she had to go on some self-actualization trips in half of the games she had been in.
Verbal-linguistic intelligence is a major lowlight for her as she really struggles with the meaning of words. It took Shantae some time to process Sky trying to get her to get off Wrench, and apparently she took a hot minute to process a Court Summons too. Her naturalist intelligence likely stinks (no pun intended) too since she considered odor (ham stink) and catching the flu as items. That's not mentioning the non-canon Ninja Mode where Shantae didn't even think to realize that the dung-covered "ninja outfit" was, in fact, NOT a new ninja outfit until Uncle Mimic brought it up. Somehow, she can avoid Darwinism though (unlike the skinwalkers that threw themselves into lava for occult reasons).
There are some lowlights that I couldn't associate with the Eight Intelligences model, like Shantae letting an egg she's supposed to babysit DIE, or that one feat of """intelligence""" where Shantae displayed a poor understanding of cause-and-effect in the Sultana's Palace and threw a fit over it being pointed out by Sky... At least she's pretty good at magic, but there's no real world model of intelligence that assesses magical capability.
That's what I know from my knowledge of the series stemming from having one game (Half-Genie Hero), along with a few Reddit disputes and debunks. I think someone more knowledgeable in the series (i.e. everyone in this sub) would answer this better. What do you think? How intelligent IS Shantae supposed to be?