Shame is simply fear of punishment. It has nothing to do with your pleasures, even if they harm or kill someone. People gleefully stone women to death without a hint of remorse when their own society allows it and cheers them on.

If your kinks were suddenly no longer taboo, and instead promoted by society as normal and accepted, your "shame" would disappear. It is simply internalizing the hatred society feels for you for being different.

For much of human history, social rejection was grounds for being tortured to death or deserted, so keeping secrets does serve an evolutionary purpose.

You have nothing to be ashamed of. In your widest dreams you could never reach the level of sadistic brutality that human society is responsible for on a daily basis.