Welcome to CC! You have a chance at any of the highly selective colleges, but so do many. They will value your ability to write and that you have consistently challenged yourself outside of the classroom with your ECs.
A 1500 is great. You could take the ACT just to see where you land, it may come in higher than the equivalent SAT.
Talk to your school counselor about your chances compared to others from your school that have been accepted to highly selective colleges, as your GPA may reflect a school with consistently tougher grading.
For your essays for Brown and others make sure to research the specific opportunities you want to explore at that college.
Create a balanced list of colleges including some of the colleges like Brown that are high reaches for all - those are easy to identify. Spend more time exploring those with 20% to 50% acceptance rates that have unique opportunities for you. That will take more work. And make sure you have a true safety you can afford and would like to attend.
Good luck from an anthropology major who has never had a hard time finding employment in various sectors over the years.