Concepts and theories are good to the extent that they can "pay for" their complexity by making more accurate predictions. How much complexity is worth how much accuracy? Arguably, it depends! General relativity has superceded Newtonian classical mechanics as the ultimate theory of how gravity works, but if you're not dealing with velocities approaching the speed of light, Newton still makes _very good_ predictions: it's pretty reasonable to still talk about Newtonian gravitation being "true" if it makes the math easier on you, and the more complicated math doesn't give appreciably different answers to the problems you're interested in.
Moreover, if relativity hasn't been invented yet, it makes sense to stick with Newtonian gravity as the _best_ theory you have _so far_, even if there are a few anomalies [like the precession of Mercury](https://en.wikipedia.org/wiki/Tests_of_general_relativity#Perihelion_precession_of_Mercury) that it struggles to explain.
Concepts and theories are good to the extent that they can "pay for" their complexity by making more accurate predictions. How much complexity is worth how much accuracy? Arguably, it depends! General relativity has superceded Newtonian classical mechanics as the ultimate theory of how gravity works, but if you're not dealing with velocities approaching the speed of light, Newton still makes _very good_ predictions: it's pretty reasonable to still talk about Newtonian gravitation being "true" if it makes the math easier on you, and the more complicated math doesn't give appreciably different answers to the problems you're interested in.
Moreover, if relativity hasn't been invented yet, it makes sense to stick with Newtonian gravity as the _best_ theory you have _so far_, even if there are a few anomalies [like the precession of Mercury](https://en.wikipedia.org/wiki/Tests_of_general_relativity#Perihelion_precession_of_Mercury) that it struggles to explain.