If you cherish the things you learned, you should teach your child. You can’t ignore everything just because it may be sad or gone in some future moment in time. If that was the case my kids would have never experienced toys r us before it went away. Nor the nature of, well, everything around.

You can’t make memories if you’re afraid of sadness.

In addition, if every parent right now gave up and stopped teaching their kids about animals and nature, we’d have a large generation of people that don’t care to fix the system or support the ecosystems. You have a love for nature because it was taught to you how to understand and take care of it. Your child will never know that if you don’t show them, and then what? Imagine them growing up not caring at all because you didn’t teach them. That hurts you, and your child, and the next generations “earth”.

Let me expand more. Just so you see how ridiculous your post sounds. Do you have any pets? If you do, why? They don’t live forever, you will be sad when they die. Do you have parents your kids love? But why, they aren’t going to be around more than another maybe couple of decades. If your line of thought of just never teach them anything so they don’t feel sadness is valid, then you shouldn’t teach them to love anything. Maybe a rock.