The Photoshop/Gimp workfow is a difficult translation. Photoshop/Gimp is a ‘raster’ (rows and columns of pixels,) as opposed to InkScape’s ‘vector’ model. Vectors are lines (curves,) that outline shapes. Vectors are ‘scale independent’, meaning that there is no resolution penalty for shrinking or enlarging them. When you ‘trace’ a bitmap (raster image,) the result is a vector image (e.g. SVG or possibly DXF.)
The curves have ‘control points’ which you can see by clicking on the arrow with 3 boxes (2nd from top on righthand vert toolbar.) These are typically ‘bezier’ curves. If you want to get comfortable manipulating bezier curves, here’s an online game that will teach you: https://bezier.method.ac/
The lines/curves are also referred to as ‘paths’. Along with shapes like rectangles, circles, etc, they are objects. The Paths menu offers a number of things you can do to and with paths, among them, ‘boolean’ operations. Boolean operations allow you to combine, subtract, break apart, get the difference, etc. of two or more paths.
It is often helpful in InkScape to select something (usually using the arrow at the top of the right hand toolbar,) and remove its ‘Fill’ (double click on fill at lower left to get the dialog box.) If the thing disappears, go to the Stroke menu and give it some color. This lets you see the lines that the CNC will be trying to do something with.
InkScape is incredibly powerful, so to manipulate drawings, it’s worth some investment in tutorials like the ones at Inkscape Tutorials | Inkscape