The Word becoming flesh, has no bearing on the meaning of "all" or "things". You have yet to show any such restriction even implied in the text.
The Word can surely come and dwell among all animal, plants, and things. If not where does the text prohibit that meaning. The burden is on you to show such a prohibition.
Wrong question. What (in the context of John chapter 1) says "things" refers to more than the humans under discussion for which the Word became flesh? You keep ignoring what the text is discussing. So where is your proof?
I can't prove it's not there, I don't need to, and would have no reason to try. If you want to believe it's implied, that is up to you. But you can't prove there is such a prohibition in the text, or can you? Show me! Point out the verse that tells you that he was speaking of men only.