most cut
s count literal characters, so for -f 6
to work, your data has to be exactly in the same columns. Not sure if your 3rd to last line is a typo or an exact reproduction of your output, but it illustrates the problem with cut perfectly.
For this case, most people will use an awk
solution:
ls -l | awk '{print $6}'
Will produce the output you have listed
The beauty of awk is that field 6 is determined by the value of awk FS variable (field separator), which defaults to "multiple white space values" (space or tab) (this is not an exact description, but is close enough for your needs).