Yes, you need to “sell” yourself, but no, the AOs are not looking to sell you a car. Ofc, If your essay is ‘you lot are everything that is wrong with world’ well, that’s not going to sell you.
Post #6 leads me to think that you are making the same mistake that many posters make about their essays: they focus too much on telling their story (of abuse, coming out, passion in life) and not enough on showing where that story is going. What have you learned from your activism so far? what have you done with that learning? how have you adapted / changed / grown? based on that, where do you see yourself going? how will that activism be used? The point is to sell you, not the specific cause. You should be able to write the essay and substitute [generic cause] pretty easily.