I remember also being stuck on the first level and then on the copy-protection. Until one day while pressing random keyboard combinations I noted that a game was saved. At the same point, my father had this XTree Gold program in the computer (like DOSSHell but better), and it had a HEX view... when you opened the .SAV file in this view, you had only like 8 or 9 bytes. I remember my excitement when I changed that 01 to 02 and boom! after loading the game I started in level 2 .
Back in school (I was in 6th grade at that time) my friends had no clue what had I done to get past that copy protection level.
It was downhill for me and cracking at that point... I was not interested in playing but more on doing reverse engineering on different games and programs.
You are being very unfair to that era. Even cutting edge software like Norton Utilities did the same, although they XORed the passwords. That passed as encryption then.
C:\> prince megahit
to get unlimited lives and level skipping.