if it was autobiographic, i don’t know to what extent it would have been.

according to wikipedia:

The character of Jon Arbuckle was envisioned by Jim Davis as an author surrogate

https://en.wikipedia.org/wiki/Jon_Arbuckle

so it’s not autobiographical, but it’s a fictional version. Interestingly, the same article says:

Davis eventually decided to replace Jon with Garfield as the main character, with the renamed Garfield strip achieving national syndication in 1978.[17] The Jon comics were published without copyright notices, making them and the prototypical Jon and Garfield characters public domain under pre-1977 copyright law.