It would be fairly easy to come up with calculus reasoning about mathematics in the way we do today, because the tools we're using to do maths is highly conduci

It would be fairly easy to come up with calculus reasoning about mathematics in the way we do today, because the tools we're using to do maths is highly conducive to calculus in particular. I wouldn't be surprised if someone kid were to intuit a bunch of major conclusions from calculus by just looking at algebra and graphs of plots. If you start with pre-newtonian mathematics, arriving at calculus would indeed be quite some feat. But then, a lot of Newton and his contemporaries were reasoning about mathematics that's fairly reminiscent of Euclid (and very alien to modern readers).