Is it smart for someone just over 20 to put $100 a month into VOO?

This stock's world is insanely confusing like holy moly. I was looking at .spx it looks safe as well. I only want long term safe investments the small research I've done had led me to this decision ANY advice is welcome. I put my first 100 in VOO using fedelity. I barely understand what I'm doing so sorry for being such a novice.