That was kind-of the point of them originally, though - it didn't matter what the source was originally, because Artificers were tinkering with magic on a more fundamental level, producing the same effect without necessarily using the same cause.
You're literally using the definition of Arcane magic to explain how Artificers go beyond Arcane magic.
Arcane magic is the scientific study of magic on a fundamental level, and using that knowledge to create various effects. That's literally what both Artificers and Wizards do to cast magic. The only difference is that artificers are more like engineers and rely on items, while wizards are more theoretical scientists and computer programers, creating rituals and formula.
Artificers have their roots in Eberron, where they were meant to be able to mass produce magic items of any kind so the setting could justify the world wide magitech advancement. So they tend to have access to traditionally divine magics simply by virtue of tradition more than something fundamentally different about their approach to magic.
What is Arcane magic, in your opinion? How would you separate what Wizards and Sorcerers and Warlocks and Bards do from what Artificers do?
Bards and sorcerers and warlocks are
weird. Honestly, they really should't fall under the same umbrella as wizards, simply because their origins are so different. Sorcerers are supposed to be... innate magic users. They don't use magical formulas like a wizard does, which means that they should access magic more like psions of older editions did. Bards, much like artificers, have a wide selection of magic and abilities from every edition that tries to define them differently that get pulled forwards. Warlocks get taught forbidden knowledge that Mankind was not meant to know.
Arcane magic is the scientific approach to magic. Divine and primal are both reliant upon powerful beings outside. Neither is a good way to describe the majority of mages.
