This is a rime; that is, it's the vowel nucleus plus coda of a monosyllable. And many rimes have phonosemantic coherence. As do assonances, that is, initial consonant clusters.
This particular one has a 3-Dimensional sense — an "ump" is something with three dimensions, roughly the same size in all three. There are 15 such simplex words in English:
lump clump dump plump hump slump jump rump
bump crumple stump rumple sump tump mump
Some of the assonances in these words are also phonosemantically coherent. KL- means 'Together', PL- means '2-Dimensional Thick', and ST- means '1-Dimensional Vertical Rigid'. So plump means an ump with wide padding, clump means an ump formed by putting things together, and — my favorite — stump means an ump that used to be a long vertical rigid thing.
See here for much, much more about phonosemantics.
First of all, those statistics from Wikipedia may be a bit misleading, depending on your point of view. What they seem to have done is count every word in a 80,000-word dictionary once, regardless of whether the word is very rare or very frequent. Consider the preceding sentences:
-First -of -all, -those +statistics -from -Wikipedia -may -be -a -bit -misleading, +depending -on -your +point -of +view. -What -they -seem -to -have -done -is +count -every -word -in -a -80,000-word +dictionary -once, +regardless -of -whether -the -word -is +very +rare -or +very +frequent.
I've marked the words of Latin or French origin with a plus sign, the others with a minus sign. That's 11 words of Romance origin out of 44 words, so 25 %. Note that regardless is dubious, because it is a word that French had borrowed from a Germanic language. Your average spoken English contains even fewer Romance words. The percentage of Germanic words generally goes up as the Romance percentage goes down.
The reason for this is that English has a very long tail of Romance words, but they are much less frequent on average than the words of Germanic origin. If you take a list of the most common words in English, they will be overwhelmingly Germanic.
As to the replacement of existing words, yes, sometimes they replaced existing Germanic words, but at other times they rather enlarged the vocabulary, especially the various technical and legal terms. The distinction is often difficult to establish, and not seldom meaningless, because many words become less frequent on their own account, so it is not always clear whether this is caused by pressure from a new word or just for no obvious reason.
The Romance words that came to England were mostly of a high register, as in law, rhetoric, philosophy, science, etc. There was the pressure from Latin on the one hand, the lingua franca across Europe, especially in writing; and from 1066 on, there was French, the language of the conquerors, who brought with them various elements of bureaucracy and high culture in French. It is usually the simpler, more frequent words that withstand such pressure the best, whence our continued attachment to words like is, the, a, he, she, do, be, have, etc.
Best Answer
I suppose it all depends on your definition of authoritative, but I think a good start is The Oxford English Corpus, a collection containing over 2 billion words of 21st century English from around the world. Here's a list of facts about the corpus, including the 100 commonest words in the English language.
Neat facts about distribution: 10 lemmas (word forms, is and are are lemmas of to be) make up 25% of the corpus, 100 make up 50%, 1000 make up 75%, 7000 make up 90%, 50,000 comprise 95% and you need over a million to get 99% coverage.
So, one quarter of all words used are the, be, to, of, and, a, in, that, have, and I.
Yeah, most of them are germanic in origin, but not all.
As you noted:
use is of Latin origin (by way of French) and replaced the O.E. verb brucan (which survives as the verb brook "to tolerate, put up with something unpleasant")
because is of direct Latin origin from the phrase bi cause "with cause."
and
people also Latin by way of French.
Those are the only words that jumped out at me. Of course, most of the common words have Indo-European origin, so they'll ultimately share a common root anyway. See two and duo.