The italian renaissance started in the 14th century for sure and maybe even in 13th century depending on who you ask. Though the exact date can be disputed, nobody disputes the fact that it started long before the fall of the byzantine empire in the mid 15th century.
And the italian renaissance had more to do with direct trade opening up between europe and china/india/etc via the mongol empire ( who had an indirect role in the creation of the ottoman empire ) than anything else. Prior to the mongol empire, they had to no direct trade with either asian centers. Instead they depended on the arabs/persians who acted as middle-men between china/india and europe. It's why we call numbers, Arabic numerals, while the arabs themselves call it Hindu numerals. The arabs got the numbers from india and we got it from the arabs. It's also why europeans used to call china cathay, which is what the arabs called china.
Trade increases wealth. Wealth increase arts/humanities. This is true for italy, india, china, europe, united states, mesopotamia, ancient egypt, etc. It's like how spring rain brings about floral bloom. The italians started getting ridiculously wealthy in the 13th/14th. And like magic, the renaissance was born.
Interesting tidbit, the mongol empire had a significant but indirect part in the "discovery" of the americas by columbus.