Please see the following list, also on WikiPedia, along with A Bijou Flashback: The History of Movie Newsreels.
These newsreels were produced by each of the major film corporations between the late 20's to the early 60's. Each Corporation used a different narrator. See my quoted example below, as Movietone and Universal/MGM are the most widely known. Most of them served as the current news for moviegoers, as these reels would run before the movie started, much like we get previews today. Most of them are known and archived because this was a major method of news that IMO reached it's prominence during WWII, as moviegoers would attend movies to check on their loved ones on the front. These reels also provided pictures from the front, which was quite a deal back then.
Notice the ad in the lower right of this movie trailer, indicating that the theater would show the newsreel before the movie for the price of your ticket.
See Movietone News:
Fox's first use of recording a news event was on May 20, 1927: Charles
Lindbergh's take-off from Roosevelt Field for his historic solo flight
across the Atlantic Ocean was filmed with sound and shown in a New
York theater that same night, inspiring Fox to create Movietone News.
A regular narrator of the newsreels was broadcaster/journalist Lowell
After Fox Films merged with 20th Century Pictures in 1935 to form 20th
Century-Fox, the name of Fox Movietone News was shortened to Movietone
In Australia, Movietone and Cinesound were competitors for newsreel
coverage, but have now combined under the Movietone News name.
Lowell Thomas, the voice of Movietone news made himself and fellow journalist TE Lawrence famous when he visited the Western Front during WWI. TE Lawrence is best known for the book and the later adaption into a movie Lawrence of Arabia
Ed Herlihy, the voice of Universal/MGM. He narrated most of the reels dealing with WWII. These are some of my favorites as he perfectly puts emotion into the attack on Pearl Harbor, and later the death of President Roosevelt. Later in life he served as the voiceover in commercials for Kraft Foods.
Update as per Comments
There is no iconic voice nowadays. The audio for a radio commercial/TV Spot is made by standing in front of a microphone and recording a voice, and then adding the voice track to the rest of the audio. The inflections etc that you here come from someone's actual voice, and with the advent of television, the announcer you heard probably works for a major network, unless the commercial you heard was local only to your area, i.e. not a national campaign.
The example you gave points to J.K. Simmons, as Tenzin, who I know as the voice of The University of Farmers - National Ad Campaign. His degree in Music, and a stint on Broadway most likely are where the roots for that voice inflection come in. As I said earlier, each example you give me will end up being attributed to a person, most likely with a degree in the stage acting, acting, or music arenas. Note that most people who do this for a living have had years of practice. As such, the only way to answer your question is to tell you there are no origins, just highly skilled people.
On that same note, I present Johnny Bravo, a.k.a. Jeff Bennett: