I don't get the CW love (not referring you). Sure, he saved OU against Texas but then flopped in 2 crucial games. He had a habit of poor decisions and seemed unable to get the ball out quickly, like ever. He was always looking for the bomb and hoping his legs would pull it out. And they did on occasions, but not enough to overcome his overall average QB play.
While the tendencies you point out (some poor decisions, trying too much for the deep ball, relying too much on his legs...) are accurate, Caleb Williams led the Big XII and was #6 in the nation in Passing Efficiency, so his play was a little better than average. I understand that OU has a high bar, especially after a run of Heisman/#1 Pick, Heisman, #1 pick/NFL Pro Bowler, Heisman runner-up/NFL Pro Bowl Alternate, but Williams was a true freshman. All true freshman make poor decisions, rely on their athleticism too much and try for the big play too often. All of them. Generally, these things improve with time/experience over the years. IMO, Caleb Williams will improve in these areas and be a great QB, somewhere.
If you look at Baker, Kyler and Jalen's true freshman seasons, you will see much of the same regarding the kinds of mistakes they made, as well as the potential they showed. In just looking a true freshman performances, you'd probably have to put Caleb in the upper half of that list, actually.
That being said, no it's not the end of the world. Just a bummer. OU will be fine, in that the team won't implode because one potential future All-American leaves. OU won't contend for a NC without Williams in 2022, but they likely wouldn't have with him either. Williams doesn't make the team good, as it will already be good. He would just make them better.