Yeah I know the Y-Wing was based on the Avenger, but I always thought it had more Stuka to it than Avenger... The 3 crew in particular always didn't jive with the YW. It's "job" in ANH was definitely more in tune with the Avenger but it wasn't a big clunky ship like the Avenger more or less was. The YW is listed as a Fighter-Bomber which is definitely not the Avenger's role. Then again that doesn't seem to mean much, and more the way they look seems to be more what ties them together.
By the way, the Black Widow definitely looks a lot more like the ARC... I don't know much about it (I don't think it was a particularly common plane during the war. Not that I'm aware of anyway), but the resemblance is striking to say the least. Right down to almost every detail... It's a different use/designation than the ARC I guess, though really the ARC's "uses" weren't explored much in the movie either.
I wasn't sure about any of the ARC's design. I don't have much material on prequal ships unfortunately.
That Black Widow pic really shows that ship's roots though, for certain.
Concept sketches for the XW, which ultimately turned up as the Z-95 Headhunter, have an interesting similarity to bubble-top fighters of the allies I find. I get a Mustang/Spitfire, or even P-47 feel to that design that didn't really totally translate to the X-Wing's final design, but still are a little more noticeable in the Z-95.