The 14th Amendment states:

All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside.

This was done to ensure slaves and their children would be citizens. Not just "freed" but made citizens. You're correct, it did not apply to Native Americans.

In 1884, an American Indian, John Elk, argued he should be a citizen by that. He lost the case. In Elk v. Wilkins, 112 U.S. 94 the Supreme Court decided the 14th Amendment did not make Indians citizens because they were not subject to the jurisdiction of the US. "Jurisdiction" does not just mean "living in the territory." It means you're part of the political system.

Indians were not granted citizenship until Congress passed the Indian Citizenship Act of 1924.

It wasn't until 1982 that Justice William Brennan kinda decided kids born to illegals were citizens.

The issue should be decided by the people of the United States. Not the Supreme Court. We should have a rational discussion about what it means to be a citizen of a nation, and the manner in which one may or may not become so. Of course that will never happen because anyone who questions the wisdom of granting citizenship based solely on geography is clearly a horrible racist and should be shouted down.