No.

They can be.

They aren't, they can be half human or were once humans, or are superhuman in nature.

Purely humans can't be a physical god based on their own physiology because you are talking of a human with almost limitless control over science. That isn't human anymore.

However, normal human can achieve Physical Godhood through technology, being able to achieve that high levels of science MPT through very advanced technology.

Then it depends how you define human. I would personally argue that, though they may have powers beyond that of a human, that doesn't necessarily change the fact that they can still be fundamentally human.

For example, say a human has Physical Godhood through a link to a being of higher power, rather than through genetics or something like that, I would argue that they are still fundamentally human.

What I'm trying to say is that power isn't necessarly due to physiology, so it is entirely possible for someone to be physically completely human in every way whilst still posessing Physical Godhood. In any case, it depends entirely on the author.

I have to say that it does depend on the author's definition of what is human. If the author sees it as mundane and mortal, then someone with Physical Godhood would probably not fit into that definition.