Are American secondary schools designed to be selective or inclusive institutions?

It is my opinion that secondary schools in the United States are designed to be inclusive through opportunity, while being selective in ability. All secondary schools are going to be inclusive for all students to receive a free and appropriate public education. However, schools are also selective in the courses that they offer. Not all students can be admitted into a gifted program. The students that are admitted into those programs must show a certain level of intelligence. The A.P and honors courses offered at high schools around the state are also selective in who can take the classes. Students must show ability through previous coursework before they can enroll in A.P and honors courses. Schools however will never deny a student an education due to the fact that they only have a certain level IQ or make all C's and D's. American schools guarantee all students and education, but they do not guarantee all students the same level of education. Some students should be placed in remedial courses while some students should be in A.P courses gaining college credits.