When working with complex illustrations it is necessary to make selections of objects. There are several ways to select.
The most immediate is to use the black arrow and click on an object, so that it is selected. If we want to add more objects to that selection, we only have to click on them while holding down the shift key on the keyboard.
Another way to do it is, without having any object selected, select the black arrow, press the "alt" key on the keyboard and draw a line that touches the objects you want to select.
Another way to select is by sweeping the objects that we want to include with the mouse: click and hold the mouse to where we want to select.
Still another is achieved by selecting an object and then clicking the right button. Then a pop-up appears that allows us to select similar objects in fill color, border color, stroke type, object type, etc.
Finally, it should be noted that you can make selections of objects as a whole or of the nodes that compose it. In that case we will have to convert the object into a path, use the node selection tool and click on the point we want to select. If we press capital letters on the keyboard we will select more points. And you can also do sweeps on the points that we want to edit.