How to interpret analog values sent to Arduino from line scanner?
First, a preliminary note: according to the datasheet, the only time you
need a delay in your program is after reading the whole array and before
sending the next sync pulse. All the other timing requirements are
shorter than a single CPU cycle of your Mega, so no need to add extra
delays.


  the camera didn't move so I assume that it should give back similar
  numbers.


Similar: yes. Identical: no. You expect noise to make every reading
slightly different, and you also will have variations due to uneven
timing of your program (e.g. the timer interrupt kicking in from time to
time).


  is there a way to determine what these numbers mean?


They are proportional to the amount of light collected by each pixel.
That's about all you know about their meaning.


  Is there some way of turning analog signals into color pixels?


No. This is a B&amp;W camera.