A presentation is a conversation.
A presentation is a conversation for which the rules of the game have one person or party doing most of the talking. A conversation is somewhat spontaneous and curvy. It's not locked and linear. It requires no script. Yet almost all of us prepare for a presentation by making a locked and linear script, usually in the form of a slide deck.
Try thinking of your content as a set of smaller ideas floating within one big idea. Give yourself the freedom to connect the ideas in any order, but let the listeners and your interaction with them guide you.