Congratulations on all you have achieved and good luck. No one can accurately chance you based on what you have provided.
I gather from what you have offered that you are an excellent writer. Hopefully that skill and passion come through in your essays because I think they will be given close scrutiny along with your LOCs.
I know this is a stressful time and I wish I could provide words to ease that anxiety. What I can offer is that Brown is a great place. So much so that decades ago it was my dream school. Ultimately they wouldn’t have me and I had to “settle” for the relatively “similar” but “inferior” Vassar. Best time of my life in hindsight and I couldn’t have had a better college experience.
My kid is a senior at Brown and I think he shares a view that his college experience was all that he could have hoped for.
My point being either way you will be fine, and that while the journey can seem daunting it will work out. Stay positive and confident please!!