Elvis's first recordings were more country music. In July of 1954 he recorded "That's All Right" which became a regional hit. Not too many people would call that a Rock and Roll record. He played at the Grand Ole Opry in Oct. of 1955, behind that song.
Elvis's first major label recording was "Heatbreak Hotel", which was released by RCA in January, 1956. Later than spring he recorded "Blue Suede Shoes", a Carl Perkins song which most people would consider Rock and Roll.
Chuck Berry released "Mabelline" in May of 1955. It was a big hit, reaching #1 on Billboard's R&B charts and #5 on the "in the stores" chart. Berry followed up with "Roll Over Beethovan" in June of 1956, clearly a rock song.
Interesting that both Chuck Berry and Elvis were influenced by Carl Perkins. Chuck toured with him in a 1956 All-Star tour, and Elvis recorded his song "Blue Suede Shoes" that same year.
Which brings up that maybe they were both following slightly behind the real beginning of the music. Wikipedia lists a whole bunch of records as candidates for the first rock record.
Because the development of rock and roll was an evolutionary process, no single record can be identified as unambiguously "the first" rock and roll record.[36]Contenders for the title of "first rock and roll record" include "The Fat Man" by Fats Domino (1949),[36] Sister Rosetta Tharpe's "Strange Things Happening Everyday" (1944),[37] Goree Carter's "Rock Awhile" (1949),[38] Jimmy Preston's "Rock the Joint" (1949), which was later covered by Bill Haley & His Comets in 1952,[39] "Rocket 88" by Jackie Brenston and his Delta Cats (Ike Turner and his band The Kings of Rhythm), recorded by Sam Phillips for Sun Records in March 1951.[40]
In terms of its wide cultural impact across society in the US and elsewhere, Bill Haley's "Rock Around the Clock",[41] recorded in April 1954 but not a commercial success until the following year, is generally recognized as an important milestone, but it was preceded by many recordings from earlier decades in which elements of rock and roll can be clearly discerned.[36][42][43]
So from my way of thinking I would not say that Elvis predated Chuck, nor really the opposite. They both came to the worlds attention in the same short period: mid 1955 through end of 1956, by which time both were stars.
‘In July of 1954 he recorded “That’s All Right”...Not too many people would call that a Rock and Roll record’
I would. At least, as a country fan as well, I would sooner call it R&R than country, even for back then.
‘”Blue Suede Shoes”, a Carl Perkins song which most people would consider Rock and Roll.’
The Elvis version yes. The Perkins version is much more country (and I never liked it as much).
As to the original argument about “King of Rock”, I agree with the historical assessment. But honestly, being the “King” doesn’t mean “granddaddy”, or “daddy”, or even the 1st one. It means “the best”, in this case, who generated the most hits and the most fanaticism (for the type, even more than the artist himself).
E.g., “King of Pop” for MJ is probably a serious misnomer, as he is nowhere close the originator of “pop” (i.e., popular music). Just recognized in his time for being hugely popular and consequently, influential.
I don’t mind calling Elvis King of R&R based on those criteria, but certainly not aghast at Berry being so. He certainly had the hits, unlike many fringe pretenders often pushed by fringe purists.