If your argument is that only things made in the image of humans can be intelligent (i.e. #1), then it just seems like it's too narrow a definition to be useful.
If there's a larger sense in which some system can be intelligent (i.e. #2), then by necessity this can't rely on the "implementation or learning model".
What is the third alternative that you're proposing? That the intent of the designer must be that they wanted to make something intelligent?
Furthermore, our history is full of instances where we invented something that a) we didn't understand and b) had uses way beyond what we intended. As a recent example, GLP-1 was intended for glucouse regulation but is now basically a wonder drug that can treat a bunch of issues ranging from obesity to addiction, inflammation, dementia, fertility and more.
Given we don't know how to define intelligence, I think it's fine to apply some "duck typing" here.