Alors, regarding the negativity, and you can call me a totalitarian, I think much of the way we see things come from our education. So I think we can actually teach children to recognize the obviousness of healthy eating. That education of course is balanced by what you learn from society and also from the dreams projected by that society. For me reviving dead animals is a useless dream.
As for environment protection, the question of being exciting is not there. It won't be exciting at all for the masses. But in the end, if nothing is done, it won't be exciting either. My idealist brain doesn't accept that but my pragmatic brain understands that we'd need some political/philsophical/sociological super powers to change that. One of those super power is propganda. We know it works (even if the examples from history are unfortunate). But then again, propaganda doesn't mean dictatorship, just look the level of communication we receive about covid.
We'd need an Elon Musk that would build a project around crowd hacking instead of sending cars to space. That's what we usually get into the form of charismatic leaders. Maybe that's what we need (or maybe I'm biased by my own personality who ikes charismatic leaders :-))
Reviving mammoths is dramatic, exciting, and overtly new and creative. It's like landing on the moon. I think it could excite people who groan at traditional environmental initiatives.
I know it's a failure of vision to see environmental protection as an essentially negative aspiration, just like it's a failure of vision to see healthy eating as essentially negative. But a lot of people see it that way, and they aren't going to willingly put their money behind reducing CO2 emissions or protecting habitat for endangered voles. Maybe for them this can be a gateway drug to giving a shit.