He might not actually have discovered or invented everything on his own. What I most likely think, is that he was more like a Director of a government program

He might not actually have discovered or invented everything on his own. What I most likely think, is that he was more like a Director of a government program or university who's tasked with key projects and allowed to interrogate or gather intelligence from anywhere. He most likely met a lot of people from both east and west, learned a few things them and decided to document them. Maybe those people also documented it in their own language somewhere but ofc it didn't survive the test of time and only way we know any of those things is through Leonardo's illustrations. The cities where he lived had influx of traders from all over the world. It's otherwise seemingly impossible for someone to come up with so many things during his lifetime.