I was told by someone who had lost a child that I could not compare it to losing both my parents [one to cancer] in my early teens because a child was more precious. Tell that to the young girl who had no idea where she would live, if she'd be able to return to school, where her next meal was going to come from and had to listen to various family members discussing how to apportion her and her siblings between several (heavily disliked and cruel!) relatives, amongst several other things I was hardly trying to say that her child was on a par with my parents - she had shared something deeply personal with me about a great loss that had affected her and I reciprocated in kind. Was that insensitive of her? Or was it insensitive of me?
Deaths affect different people differently. My dog died when I was 12 and I was absolutely devastated and needed ridiculous amounts of comforting from my mother. My mother went on to die later that year and I was much stronger on the face of it when that happened as opposed to the former. Does that mean that my dog was more important than my mother? No. It just means that I reacted differently to different deaths. My father died a few years later. That affected me much more than the death of my mother but, on the face of it, it did not look like it. Did I love him more than her? No. Again, it just means that I reacted differently to different deaths.
OP, YABU and snarky.
As to the point about card placements, they have sections for birthdays, loss, illness etc. A loss is a loss, be that a child, parent, partner, spouse, pet etc. All because you may not feel that the loss of a pet warrants a card [in the same spot] does not mean that others think the same. Perhaps, like the woman I mentioned in my earlier post, you would expect "Sorry for the loss of your mother" cards to be placed elsewhere to "Sorry for the loss of your child" cards in case someone buying one or the other gets offended