I don’t fully understand what sexual attraction really is

In one occasion I was able to pierce through a feeling of arousal and I found a big wound from my childhood. Something totally non sexual.

I wonder whether a lot of sexual attraction just points to unmet needs and is “designed” to help us meet those needs by bringing closer to specific people (with certain characteristics).

But I don’t understand the whole picture here. Is it always like this? There is some clear use for sexual arousal in reproduction, I can’t believe that’s always a sexualized childhood wound. Where’s the border between a sexualization and a genuine, irreducible sexual thing?? What do you think?