Screenrant also said that Siegel's pitch in 1938 was for a Superboy newspaper strip.
They were relying on the book SUPER BOYS (2013), by Brad Ricca, for some of their research. However, the Screenrant article often misspelled "Siegel" as "Siegal"--so I didn't know if I should put stock in their work, since they couldn't even get a simple thing like that right.
And other sources said Jerry's 1938 pitch was for a comic book feature.
Still, given that Siegel and Shuster had always wanted their own newspaper strip (which is why they didn't originally sell Superman to National Allied for their comic books) and given that a Superman strip had yet to see the light of day in 1938, it's an attractive proposition that Jerry wanted their newspaper strip to focus on the young Boy of Steel's adventures.
Siegel might have considered that the better option, since newspapers appealed to the whole family and strips featuring kids as the stars were very popular. This also would have played to one of Joe Shuster's strengths, as he had a humourous way of drawing kids.
I remember reading somewhere (but I can't remember where) that Jerry's original vision was for Superboy to be a little trouble-maker--an agent of chaos ŕ la Little Rascals, Dennis the Menace, Bugs Bunny, I guess. More like Mr. Mxyztplk or the eventual stories of Superbaby.
The proposition that instead of a Superman newspaper strip (or in addition to one), there could have been a Superboy strip suggests a very different scenario. What if readers loved the Kid from Krypton more? Superboy might have become the default version of the action hero.
Given that the story in MORE FUN COMICS 101 is only five pages long and most of that is a retelling of the origin story, I would guess that Jerry's original 1940 script was partly based on the origin in the first issue of SUPERMAN (1939) and in the newspaper strip's 1939 origin story. So the parts of the script that would most likely be Siegel's are those that resemble the 1939 version of events. If Don Cameron added to the script, it might have been in the names Jor-El and Lara rather than Jor-L and Lora, or in how the story quickly wraps up.
Five pages is a pretty short story, even in those days, so Jerry probably had written a much longer script which Don Cameron chopped down to fit the available page count. The reason for this short length was because they had pulled the scheduled Dover and Clover story from the issue to make room for Superboy and five pages was all they could spare. Note that Dover and Clover's names still appeared on the cover while Superboy's didn't--proving this was very last minute and a bit cloak and dagger.