I don’t think that the kindness topic was a mistake at all. In any career, this is crucial, perhaps more important than all the traits that the grueling college application process selects for. I think it was a brilliant idea to write about this, and I hope that the sincerity of it came across well in your essay.
Who knows why the schools wanted one person rather than another? You got into a fantastic school, with tremendous opportunity, and you’re being given a full ride!!! You should be doing the dance of joy.
One thing that you might think of, now. You’re going to want some pocket money when you are at school. Unless you have some incredible career-enhancing volunteer opportunity that sucks up all your hours, maybe you should get a part time job now, and plan for a full time job this summer, to earn and bank some money before you go. Even though you’re being given a full ride, it’s nice to have some extra money on hand for expenses that you might not have expected. Right now, you’ve maybe got a bit of a break from college applications resume building, and aren’t expected to get a wow-factor internship at this time. So it’s a good time to earn some pocket money.