Since the OP is asking for a list of iconic/revolutionary/important racquets that go back 100 years, when none of us were around, with the possible exception of Coachrick

, the candidates proposed so far (all of them very good) are a little thin on the really early stuff, and understandably so. The difficulty is not in finding iconic and/or important early racquets, but in deciding which of the recent GROATs should yield its pedestal to a long forgotten one (the "apples vs oranges" dilemma). It is a largely subjective exercise. As I remember, Joe Sch's site (woodtennis) used to have a nice GROAT list for every decade since the era of Major Winfield, which would be a good place to visit for the OP. I'm not sure what happened to it?
For me, these oldies below deserve a spot or two on the "Best of the Century" list:
1920 Wright & Ditson aluminum, the first aluminum racquet in the world, earlier than the iconic Birmal.
1922 Dayton steel, not the first steel frames ever, but they stuck around longer than all others.
1935 Hazell Streamline, the highly sought after brainchild of Frank Donisthorpe, who also experimented with the first ever oversized frame.
1940 Andreef Speedshaft, the first ever "modern"-shaped racquet, cleverly designed and attractively made, appropriately modeled by the equally well put together Liz Taylor here:
Among the more recent offerings, I would have included some of the earliest all synthetic frames, which fundamentally changed the industry, if not the game itself.
1972 Voelkl Zebra, not the first all synthetic frame to be developed, but it was the first to be in production and to reach the market.
1975 Aldila Cannon and Tony Trabert C-6 - the first commercially successful all synthetic graphite frames.
1979 (Pro)Kennex Black Ace - the opening (and very successful) salvo of Taiwan's conquest of the racquet market. To paraphrase Louis XV: Après le Black Ace - le déluge!