On a typewriter from around the time of the first Macs, the return key normally moves back to the beginning and moves down a line, so that's probably why they picked it. They also called the key "return" rather than "enter."
On another note, I find it incredibly weird describing an "everyday" item like a typewriter because many people on HN may have never used one!
On later type writers both the line feed and carriage return were integrated into a single key or lever, which was just called carriage return or return. From this perspective, an encoding using a lone CR for newlines might make more sense than one using a lone LF. But neither combination really makes intuitive sense in buffered, electronic systems. It's just how it is.