Shigeru Miyamoto previously explained why Star Fox was Star Fox and not Star Man or Star Robot, and it's all thanks to Gundam, Star Wars, and other Sci-Fi that were popular before the game began development.
Following the announcement of Star Fox – the new remake of Star Fox 64 – Twitter user Genki_JPN resurfaced and translated an old Iwata Asks interview from the release of Star Fox 64 3D – the old remake of Star Fox 64 – in 2011, where the developer recalled how Star Fox got its identity. Miyamoto recalled that he suggested to designer Takaya Imamura about putting animals in the pilot's seat for their space shooter
"At the time some people said 'It would be cooler if it you made something with robots,'" Miyamoto explained, " But what was important to me was that, after Star Wars and Mobile Suit Gundam had already appeared, and with so many hit works already depicting the world of science fiction, I thought 'We're going to create our own original science fiction!'"
Miyamoto added, "I didn't want to make it like any other existing sci-fi game adaptations. So, the only option left was a fox." He mentioned elsewhere in the interview that the Fushimi Inari Taisha shrine was around a 15-minute walk from Nintendo's office back in the day, as well as a local baseball team called "Inari Fox," leading to Miyamoto picking a Fox for the project.
Meanwhile, the game's script writer, Mitsuhiro Takano, recalled that Imamura took inspiration from folklore and fairy tales for Peppy and Falco being a rabbit and a pheasant. As for Slippy, Miyamoto recalls Imamura drawing a frog and saying those are good too.
Of course, it's a gambit that paid off as Star Fox's cast of characters would go on to become some of Nintendo's most popular, and not just because Fox and Falco were busted in Super Smash Bros. Melee.