John he was born May 26, 1907, making him 38 at the outbreak of hostilities - with a family.
After France fell in 1940, Congress enacted a pre-war (sometimes called peacetime) draft; conscriptees only had to serve one year. In 1941, by a one vote margin in the House, Congress extended the one-year draft. After Pearl Harbor, Congress extended the draft to men age 18-38 (at one point, 18-45). I would note the married men were not drafted after age 35.
I would also note that Wayne applied to the U.S. Naval Academy, (1924 or 25, I’m not sure) but was not accepted.
Wayne was exempted from service due to his age (34 at the time of Pearl Harbor) and family status, classified as 3-A (family deferment).
As for him being an average actor - I’ll leave that up to you. I’ve known him to be a likeable and considerate man.
At the time of Pearl Harbor, Wayne was 34 years old. His marriage was on the rocks but he still had four kids to support. His career was taking off, in large part on the strength of his work in the classic western Stagecoach (1939). But he wasn’t rich. Should he chuck it all and enlist? Many of Hollywood’s big names, such as Henry Fonda, Jimmy Stewart, and Clark Gable, did just that. (Fonda, was 37 at the time and had a wife and three kids.) But these were established stars. Wayne knew that if he took a few years off for military service, there was a good chance that by the time he got back he’d be over the hill