Inventors and heroes

The current consensus is that Newton and Leibniz invented calculus at more or less the same time, independently of each other, but (in the English-speaking world at least) Newton had better publicity.

Interestingly, they also had very different ideas of what calculus was good for. Newton wanted to use it to model the physical world, while Leibniz seemed to think it had more metaphysical/philosophical significance. Arguably, they were both right, because the notion of Taylor series and analytic continuation have greatly improved our intuition and understanding of What Functions Are... and that has in turn been used to bring complex analysis into the world of physics and engineering (e.g. in the form of modern Fourier analysis). It's all connected in the end.