26 Singers, 26 Letters According to RollingStone, below are the 26 greatest singers of all time:
Aretha Franklin         Al Green
Ray Charles             Robert Plant
Elvis Presley           Mick Jagger
Sam Cooke               Tina Turner
John Lennon             Freddie Mercury
Marvin Gaye             Bob Marley
Bob Dylan               Smokey Robinson
Otis Redding            Johnny Cash
Stevie Wonder           Etta James
James Brown             David Bowie
Paul McCartney          Van Morrison
Little Richard          Michael Jackson
Roy Orbison             Jackie Wilson

You can get this as a list of strings here.
Task
Given a singer name, print or return a letter from A to Z which uniquely identifies this singer. (If your code returns A for Bob Dylan, then it cannot return A for any other singer.)
As opposed to other similar challenges, the mapping is up to you as long as it's collision-free.
Rules

The input is guaranteed to be one of the 26 singer names listed above with this exact spelling and without any leading or trailing whitespace.
You may output the letter in either lowercase or uppercase. But it must be consistent.
You are encouraged to provide a test suite for all 26 possible inputs.
This is code-golf, so the shortest answer in bytes wins!
Python 2, 80 71 bytes



def f(s):i=sum(map(ord,s))%98%40;return chr(i-i/26*18+i/32*3-i/37*8+65)


Try it online!

The sums of ordinals modded give numbers between 0 and 38

The numbers larger than 25 are then shifted to fill in the blanks as below (sorted sequence shown):

  0  1  2  3  4  5  6  7  8  -  -  -  - 13 14  - 16  - 18  -  -  - 22 23 24 25  - 27 28 29 30  - 32  - 34 35 36  - 38


Subtract 18 if i&gt;25:

  0  1  2  3  4  5  6  7  8  -  -  -  - 13 14  - 16  - 18  -  -  - 22 23 24 25
                          - 27 28 29 30  - 32  - 34 35 36  - 38


Add 3 if i&gt;31:

  0  1  2  3  4  5  6  7  8  -  -  -  - 13 14  - 16  - 18  -  -  - 22 23 24 25
                          - 27 28 29 30  
                                                  - 32  - 34 35 36  - 38


Subtract 8 if i&gt;37:

  0  1  2  3  4  5  6  7  8  -  -  -  - 13 14  - 16  - 18  -  -  - 22 23 24 25
                          - 27 28 29 30  
                                                  - 32  - 34 35 36  
                                            - 38


Which gives the sequence 0..25

  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25


These are then converted to A-Z with chr(i+65)