Ooh, this is a good one.
I don't think humanity 'deserves' anything per se, but living things ought to have the opportunity to flourish, and that includes the individuals that make up humanity.
I think most people could be better and happier under different conditions, and am, I suppose, optimistic enough to believe that its something that could be realised to all except those most dedicated to the oppression of others.
The fact that so many humans (and other animals, and natural systems) are constantly subject to harm, coercion, and the denial of choice at the hands of others is unacceptable to me.
I don't know that I'm trying to make the world a better place very effectively - I tend to pick small, personal battles, tiny causes that only affect a handful of people, and am demonstrably less reliable and effective on the big picture. But I try to be kind and to protect others. I've failed a lot over the years.
Spite is a powerful motivator. You can go a long way on spite. Spite can help you survive. It's not my primary reason for trying to improve things, but I suppose I would like to help make the kind Utopia my ideological opponents would detest.
And everything I do is in service to being the kind of person I want to be. I'm a continuous work of self-improvement, having started from a rather shitty place. If I can't try to fix myself, what chance have I at helping to repair and nourish anything else?