TLDR: You can't really (but you can kind of*)
In vector image editing software, all lines, or shapes, are constructed using the concept of vector paths, to which fills and strokes are applied. That's how the software works. There is no way to create lines without them being paths. This applies not just to Inskcape, but also Illustrator, CorelDraw, and other similar vector image editing software.
If you don't want to use paths, then have a look at raster image editing software, such as GIMP (which is free) or Photoshop. With these you can simply draw lines with the brush, and other tools without the need to draw paths. Note that raster images are made of pixels (unlike vector images).
*It is possible to link or embed raster images in Inkscape and other vector image editors, but these will remain as raster images made of pixels. It's also possible to rasterize objects made in Inkscape using Edit > Make Bitmap Copy, but again these will then be made of pixels, and not vector.
Here's some further reading to help you understand the differences between raster and vector images