I am surprised that you honestly can't tell. I find this sincere. There are a few such things on the list, like modern firefighting and renewable energy from engineering microbes. So if we aren't cherry-picking, it's a varied list.

Moreover, it isn't always as easy to say what is the biggest idea. If we truly learned to communicate with animals, I can see that having the potential to radically decrease suffering in the world for example.

Instead of complaining some people's ideas aren't good enough enough, see it as a challenge to publish some of your own, you got some good problems there.

I actually loved this list and article, and what I like the most about it was the unpretentiousness of actually proposing real ideas, versus saying something that would sound admirable, but actually not really be an idea.