I imagine it would mean to take an element of someone's culture, and then adapt it to your own use case that allows you to benefit from it, even if it shines a light on some sort of negative stereotype. Is that a decent definition

It's missing a key part, which is the decontextualization of the cultural element being adopted.

In another comment you wrote "Please, by all means, spread matzoh ball soup as far and as wide as you can. It's delicious." What if I took a recipe for cholent, added sour cream and cheese and some kind of shrimp ball, and sold it to people under the name "Authentic Jewish Matzo Ball Soup"? Imagine if that food product exploded in popularity and suddenly people that have never interacted with Jewish culture or food are talking about and making a "matzo ball soup" that contains beef, dairy, and shellfish (but no matzah).

That's all fine, to you, I'm sure.

Not all cultural appropriation is aggressive. Cultural exchange happens and not everything keeps cultural context. Japan loves to adopt bits of other cultures without context, and I don't think people are upset about that.

An imbalance of power can compound the issue. Back to the bastardised soup. A "regular joe" altering a recipe for a traditional Jewish food to repackage it and sell to a wide audience can be excused in a number of ways. But what if a violent antisemite was engaging in that kind of behaviour? Would that change anything for you?