In an effort to pin down what year the balance tipped, I will attempt to fill in some more of Stonewall's 1905-07 cohorts as Lost or GI (or more precisely, Nomad or Hero archetypes). Even I can't finish the list-- Perhaps others can pick up where i leave off? My fill-ins are in CAPS:
03-Jan-1905 Ray Milland - ??
04-Jan-1905 Sterling Holloway - ??
12-Jan-1905 Tex Ritter - Lost?
02-Feb-1905 Ayn Rand - LOST (fits the "crusty conservative S&H model to a T)
10-Feb-1905 Lon Chaney, Jr. - Lost?
29-Mar-1905 Philip Ahn - ??
15-May-1905 Joseph Cotten - Lost?
16-May-1905 Henry Fonda - GI
21-Jun-1905 Jean-Paul Sartre - Lost
02-Aug-1905 Myrna Loy - Lost?
25-Aug-1905 Clara Bow - Lost
18-Sep-1905 Eddie "Rochester" Anderson - ??
18-Sep-1905 Greta Garbo - Lost
07-Oct-1905 Andy Devine - ??
17-Oct-1905 Jean Arthur - ??
05-Nov-1905 Joel McCrea - ??
19-Nov-1905 Tommy Dorsey - Lost?
24-Dec-1905 Howard Hughes - Lost?
28-Dec-1905 Cliff Arquette - ??
28-Dec-1905 Earl "Fatha" Hines - ??
14-Jan-1906 William Bendix - Lost?
15-Jan-1906 Aristotle Onassis - Lost?
02-Feb-1906 Gale Gordon - ??
04-Feb-1906 Clyde W. Tombaugh - LOST (he was the astronomer who discovered the planet Pluto-- pretty much a loner's job)
26-Feb-1906 Madeleine Carroll - ??
06-Mar-1906 Lou Costello - GI? (No-- I'd call him Lost actually)
16-Mar-1906 Henny Youngman - GI?
20-Mar-1906 Ozzie Nelson - GI
04-Apr-1906 John Cameron Swayze - GI
13-Apr-1906 Samuel Beckett - ??
03-Jun-1906 Josephine Baker - very LOST!!! She could almost be described as the last saeculum's Mariah Carey
22-Jun-1906 Billy Wilder - ??
05-Aug-1906 John Huston - Either?
25-Sep-1906 Dmitri Shostakovich - Lost?
05-Dec-1906 Otto Preminger - Lost?
06-Dec-1906 Agnes Moorehead - Either?
27-Dec-1906 Oscar Levant - ??
03-Feb-1907 James Michener - GI
15-Feb-1907 Cesar Romero - LOST (he had the same sort of vaudevillian comedic edge that Abott and Costello, George Burns and the Marx Brothers had)
22-Feb-1907 Sheldon Leonard - ??
22-Feb-1907 Robert Young - GI?
28-Feb-1907 Earl Scheib - ??
12-May-1907 Katharine Hepburn - Either?
22-May-1907 Sir Laurence Olivier - Lost?
26-May-1907 John Wayne - GI
16-Jul-1907 Barbara Stanwyck - GI
29-Jul-1907 Melvin Belli - GI?
15-Sep-1907 Fay Wray - Lost?
29-Sep-1907 Gene Autry - Lost?
25-Dec-1907 Cab Calloway - Lost?
I'd give the nod to 1907 for the Lost/GI boundary-- I see Nomad archetypes outnumbering Heroes in 1906, at least among people of notoriety.