as noted the term Bowie has become to mean many types and was even so back when. While some of the other Bowie students/aficionados will/may disagree, IMO Norm Flayderman's book. The Bowie Knife, Unsheathing an American Legend is one of the best resources currently available since he offers a bunch of actual period documents.
The disagreements over this book apparently are mainly based on the fact that Flayderman used his own collection for the images and two his research into the whole James Black "mythos" that has caused so much controversy.
Regarding clip point blades, the style is far older than the Schively or any other 19th Century Bowie for that matter. The pattern dates back to the Middle Ages at least. There is an early dark ages seax blade in the British Museum that unless you knew it was from that period one would swear that it was a classic 19th Century Bowie with a clip point. And guards despite "common knowledge" are not a 19th Century innovation. IMO the English were the most likely "culprits" when it came to that particular style blade as being a Bowie (or Arkansas Toothpick), but there were also American maker's producing clip point Bowies by the early 1830's in direct competition with the English. And FWIW English made Bowies were being heavily imported to the US by the mid 1830's although sales increased even more in the 1840-160 era/.
As for the original Sand Bar Bowie, Rezin, Jim's brother described it thusly
Rezin P. Bowie, Planters Advocate: August 24, 1838:
The first Bowie knife was made by myself in the parish of Avoyelles, in this state (Louisiana), as a hunting knife, for which purpose, exclusively, it was used for many years……The length of the blade was nine and one-quarters inches, its width one and one-half inches, single edged and not curved.
- as Tim noted the earliest documented Bowies are not what one normally considers a Bowie i.e. the "classic" clip point Bowie. The original Bowie as described by Rezin (pronounced reason BTW) and along with the earliest documented examples of Bowies (many if not most commissioned by Rezin) have blades that are more like what we now commonly call a French chef's knife. The style is more a typical Mediterranean area style blade, that again goes back at least to the Middle Ages, rather than the classic Musso or Iron Mistress style clip point blade (that movie and the book on Bowies by Raymond Tharpe, have for better or worse heavily colored our image of what an original style Bowie was/is despite the historical record. That style blade is one that would in fact have been very common ione n Louisiana, home of the Bowie clan, with it's heavily French and Spanish influence, whereas clip points are again mostly an Anglo style. The early and documented Searles blade for one is a good example of the Med style.
IMO so much "bad" and mediocre info has been written over the years about the subject (including a lot of the footnotes on Wikipedia) that it's often hard to wade through the blather at times and frankly ALL references and experts need to be checked and cross referenced (and taken with a grain or two of salt) no matter who the author is or what the subject is.
To add to the confusion, over a relatively short time the term Bowie became a generic and marketing term for any large bladed knife or in the case of the San Francisco styles as made by such makers as Michael Price, any "fighting" knife. Generic in much the same way Coke became "the" name for any cola drink whether it is made by Coca Cola, Pepsi, Shasta, RC, etc.
IMO unfortunately this is also one of those subjects that can get VERY heated and set passions on high. I've come to my own conclusions over the past fifty years of research into the subject (they are not written in stone though), but I generally keep them to myself because I'm just not up to dealing with the heated (oft times over heated) emotions about the subject that get in the way. Overall my attitude is to delve into this or any subject with as an open mind as possible and let the facts, and not just opinions (no matter who's) with out verified substantiation, speak for themselves.
[They are about the size of a common English carving knife, but for several inches up the blade cut both sides/quote]
FWIW that cut up both sides is a common feature on Med style blades, including Spanish Belduques. Th term in and of itself does not necessarily describe a clips points, which may or may not be sharpened along the back edge - in modern parlance such a clip without being sharpened is termed a false edge.