How come Spock is the only one with pointy ears in Star Trek?

Answer 1

In Star Trek TOS, Mr. Spock is the only main cast member who is not human. He is a Vulcan, and Vulcans have pointed ears.

There have been other characters on the show with pointed ears, but none of them were main or regular characters.

Answer 2

While by no means the only one, Spock was the only Vulcan among the original crew (there were several appearing in the movies, most notably Lt. Saavik.)