Feelings aren't instinct. (Feeling disgusted or sexually aroused or aggressive isn't an instinct.)
Instincts, by definition, are complex behavior. (Think birds building nests; nobody teaches them to do that, they are born with that knowledge.)
Sexual arousal is neither complex nor behavior. It is a simple hormonal state.
You're using a colloqual meaning of "instinctive" that is unscientific and wrong.
But that's far from being the only source that defines 'instinct' in a way that doesn't align with what you're proposing.
Humans do have instincts.
[1] https://www.britannica.com/topic/instinct/Instinct-as-behavi...
Including the possibility that Gandalf and Harry Potter fly in on a Raelian flying saucer and solve climate change for us.
In reality, however, no instinctual behavior has yet been found in humans.
https://en.wikipedia.org/wiki/Instinct#In_humans