Okay. But I've never seen anyone fault Newton for failing to say explicitly that he's not saying where gravity comes from.
His science didn't need him to say that. Which is fine, because origin questions do not fall into the range of direct observation/testability/verifiability anyway.
You are aware, I imagine, that Newton — a strong monotheist — personally believed that the universe and all things in it (especially including its laws) is a divine creation; not only did God make it, but Newton believed God was eternally, directly involved in sustaining it. But as I said, this belief was not relevant to the conduct of his science, which dealt with the universal physico-mechanical laws. Gravity was a "given" for him. Like life was a "given" for Darwin.
We wouldn't use Newtonian science to show the origin of gravity, any more than we would use Darwin's ToE to show the origin of life. Neither is an "origin theory."