For fake SINs, I could see starting with one rating: 3 or 4 fake SIN, and one lower-rated everyday/throwaway fake SIN, but it is not really essential. I think you might be looking at a lot of "nice to have" things as "absolutely essential for survival" things. The importance of Resources is subjective and can vary from campaign to campaign, but here is how I see it:
E with no Karma: Literal street people - murder hobos, neo-Luddites with limited experience in urban areas such as shapeshifters or recently-arrived-to-the-sprawl tribal shamans, barrens dwellers, or people who have been suddenly and violently displaced from their previous circumstances.
E with 20 Karma: The basics - armor, a gun, a bike, a fake ID, a commlink, a low lifestyle, and some other inexpensive gear. Unaugmented combat adepts, mages without foci, other street level or starting shadowrunners.
D: Adepts with a Qi focus, mages with a spell, spirit, or sustaining focus; characters who have very light augmentation, and characters who are not deckers or riggers, but who need extra gear to do their job - cover ops specialists, demolitions experts, street docs, etc. Also characters who are otherwise similar to E + Karma, who need a single more-expensive item such as a monofilament whip or a good rifle.
C: Sammies with cheap augmentations, adepts with an essence point's worth of augmentations, mages with a power focus, and characters who are either well-to-do or who require more extensive gear (a sniper who is also a covert ops specialist, etc.).
B and A: Generally, these will be exclusively deckers, riggers, and street samurai.