He was not left wing. The parties have shifted dramatically the left since 1960. Most of the Democrats in 1960 were to the right of present day Republicans. You need to understand that.
He was left-wing by 1960 standards, sir. There hasn’t been a Conservative who won the Democrat Presidential nomination since 1924, that being ex-WV Congressman and former Solicitor-General John W. Davis. Before that, the last Conservative Democrat nominee was then-ex-President Grover Cleveland in 1892. Since 1896, every Dem nominee (save the above two and a fence-sitting squish in Alton B. Parker in 1904) has been a left-wing Democrat.
The Socialists hijacked the Democrat party during Cleveland’s second term (so much so they told him he could forget being renominated in 1896). They’ve been effectively Communist since McGovern in 1972. You’ve had some on the center-right, but they spent a century running them out of the party, and haven’t won the nomination in 94 years for President.
Please don’t try to sell “But JFK was a Conservative.” It doesn’t pass the smell test. Had he lived to 1972, he’d have backed McGovern and every other loon to date (including Zero and Hillary).