I’m pretty sure my hands are not too small compared to the average human. I went as far as researching that, in a quest to answer the question “Is it me?”. The average length of an adult male’s hand is 7.6 inches (19,3 cm). For females, the average drops to 6.8 inches (17,2 cm). Let’s say I’m well within those averages. This has brought me some comfort: it’s not my fault that I’ve dropped my phone 26 times until the screen looked like Schwarzenegger when he removed his skin in Terminator. It was both scary and disturbing.
If then the 7 most promising small smartphones for 2020 have an average diagonal distance of more or less 6.3’’ (16 cm), and the average human thumb is more or less 3.11’’ (7,8 cm), there’s clearly an issue here. The smallest smartphone of 2020 is the iPhone 11 Pro with 5.8’’(14,7 cm) and the biggest phone is somewhere around 6.8’’ (17,2 cm).