It took me longer than BillD's 12 seconds because I felt that I had to read what I posted before putting it up here.(smirk)
The Wiki contributors refer to the QWERTY as being "left handed" with more English words being possible with the left hand alone than with the right hand alone. Some earlier articles (50 years ago?) maintained that this was deliberately done as the layout "matured" in recognition of the common "greater dexterity" of the "off-hand" in most people.
Just as a right-handed fiddle is bowed with the right hand (where strength and "gross motion" are the requirements) and fingered with the left (where dexterity is the main need) the early experience with "almost QWERTY" layouts indicated that for the mechanical typewriters of the period it was preferable to have the most frequent/rapid movements on the left (for mostly right-handed typists).
Reports ca. 1950 - 60 asserted that Sholes and others who evolved keyboard layout to modern QWERTY were familiar with "letter frequency" studies and at least one patent from the early era cited "letter adjacency" in arguing that one of a pair of letters that nearly always appear together should be moved so that they weren't both "on the same finger."
While there was some knowledge of character frequency and adjacency characteristics in English at quite early times, the common use of "substitution cyphers" to send "coded" messages by the time of the US Civil War, and the use of "character counting" for breaking such codes, made the concept quite well known (by some) by the time the typewriter was beginning to reach a developed state. It's reasonable to believe that early keyboard designers were among those aware; and the "modern QWERTY" keyboard does a pretty good job of applying the notions of dispersal of frequent characters, separation of adjacencies, and distributing the characters where some "differential dexterity" is recognized.