They’re not the required medium for your presentation; you are.
When you’re giving a presentation or pitch, please don’t confuse the slides with the substance of the thing that you are talking about. The slides are not the presentation.
The presentation is a series of ideas and concepts, the place you want to take your audience to, it’s a course of action that you want them to take immediately after your talk, but you might not need slides to do that. You might not need anything. You might have a prop, you might do something on a whiteboard. Please don’t think that the slides are the presentation itself. They might be incredibly useful. They might quickly convey a lot of information. There might be some wonderful images you can show, but they are not something necessarily that are vital for your talk.
So please, have a look at your material and think: ‘could I convey this without the slides?’ ‘Do I even need slides at all?’ Please remember the slides are not the presentation. You are the medium for this talk or pitch. Focus on having the ideas in your head, ready to deliver, and on making your delivery as engaging as possible.