It's a Fantasy world created in Japanese media around the same time as the Final Fantasy series. They probably drew from similar areas of inspiration.
It's like Lord of the Rings and Narnia. They were created around the same time by people who were really good friends and taking inspiration from similar areas of interest; mythology, history, conservationism, Christian philosophy and the scars left by the Great War. So Tolkien and Lewis created series with a similar vibe.
A lot of Japanese media from around the 80s has themes of adventure and boundless potential, exceptional individuals becoming powerful through hard work and mixing tropes from classical Japanese and Chinese culture with European Fantasy tropes and American media. If you look at the socio-economic stuff that was going on in Japan at that time (massive boom economy, a generation growing up with a lot of western culture and literature, but finally the stigma against traditional Japanese culture that had been around since the WW2 going away, so martial arts becoming fashionable again etc.), you'll probably see patterns that explain why. For starters, it's very likely both Toriyama and the creators of FF were inspired by the manga of Osamu Tezuka and were influenced by the style, tone and themes.
Also don't forget, that Toriyama, the creator of Dragon Ball was involved in videogames in a similar genre; he was the artist on a lot of the Dragon Quest series, and then would ultimately work with a bunch of people from JRPGs in the mid 90s to create the masterpiece that is Chrono Trigger as their character and monster designer. There was a fair bit of crossover between manga and games because the creators share similar interests.
