to create a better future for all members of the human race.
This part is a little cumbersome. "all members of the human race" can be accomplished with the word "all."
So it is hard to justify a large, cumbersome phrase. I know it expresses something, but I think you can do better with that sentence. Express something practical/pragmatic, maybe.
I look at the essay for a long time, and it is hard to say how to improve it because you have a nice writing style. Now I think the only way I can help is to challenge you with brevity.
Find places in the essay where you can accomplish the same thing in fewer words. Imagine how cool it can be if you accomplish all the same things in half the words. It would be an intense experience for the reader.
Throughout my life, I have always found myself happiest when helping others or in a team setting, working together towards a positive goal.------Here is a sentence that needs to be said in fewer words.
I am happiest when I am working with a team toward a meaningful goal...
Brevity is powerful.
Other than the need for some brevity, this is very impressive!
Even right here you have a chance to cut some unnecessaries:
I am aware that
dedicating twenty seven months of my life to these months of service will be very challenging but I am confident that I will be able to meet the ten core expectations for volunteers.---- you don't get to include 27 months if you cut that, but who cares? They know it is 27 months. So... be very picky with the words and phrases you allow to participate in the essay.