Cura isn't meant to build models, it takes models to prepare for your printer (rotate, adjust speed and layer height, infill pattern, external supports, temperatures, etc) and slices them into g-code that the printer uses to print. For hobbyists it's the best free software of it's kind. The next step from Cura is the paid software simplyfy3D which some find easier to use and more customizable.
To build models you would need a 3d program like Fusion360 (free for hobbyist but it is professional CAD). TinkerCAD and Sketchup are easier to get into and are web based.
Thingiverse is about 1000x more populated than the next listing site so it's pretty much the only one talked about.
The Creality Ender Pro is a fantastic printer, great choice.