No, South Americans like Colombians aren't considered traditional URMs. As an immigrant and first gen college student, you have a great story for a diversity statement that will serve as another way to convey your diversity.
Just throwing this out there - knew a guy who had a 2.7 GPA from a meh undergrad institution. Got a 177 on his LSAT, got into every T-14 school besides Stanford and Yale (yep, got into Harvard). He now goes to UVA because they gave him a full ride.
Another issue is the devotion to legacy students (for alumni donations). Harvard's undergrad class of 2021 is 29.3% legacy. I'd be interested to see the percent of law school legacy students.