The majority of words that came into the language following the Norman Conquest were often directly borrowed from Latin"

is the same as saying

Most Latin derivatives directly incorporated into English are coined after the Renaissance.

It would seem then that you are confirming my view that Norman French did not significantly contribute to the English language. Speaking of which, of the 50% of Romance terms in the English language just how many are Norman French Petraites? Can you even say? You have YET to prove your point.

For each and every Norman French term you list I can find an Old English word with the same meaning. That would make Norman French no more important than Old Norse. Iwould say Old Norse would rate more importance as well, considering it changed some of the more basic things in English such as pronouns, not to mention forever changed the way the language was spoken.

As I said though, Old English has synonyms for each of the Norman French terms you name. In the case of Native American words, that is not the case. So now are those Norman French terms truly "ever so slightly more significant than "guano?" I do not think so. Middle English speakers could and often did just fall back on the native terms, and so could we had we a mind too. Hell, some of the native words survived into early Modern English.

Lets look at your Norman French words that supposedly introduced new concepts to the English

crown = Old English cynehelm
power = maegen
court = dómsetl
minister = wita (or stigeweard or countless other terms)
council = mæþel
nation = þéod
army = fyrd or here

I could go on, but any rational individual would get the point that all the concepts behind Norman French words you name already existed in the English language. They did not come over with William the Bastard, and thus their usage in English is truly of little consequence. Had they never been borrowed, we would have just fell back on the native Germanic terms.

However, without the Native American words, we would be hard pressed to describe many things our World knows to exist that we did not know existed in 1200. That is they are new concepts (not old ones with a new alien name). As I said look at the OED (the multi-volumn set Not the pocket version). I think you would find that many of our basic foods and their names come from Native American languages, not to mention place names, and so forth. And as a test just try and come up with one Germanic term for squash or potato.