You can also use Apple Freeform to create shapes and icons and copy/paste them into Scapple. Also, Control-Command-Spacebar to use emojis and copy/paste them into Scapple.
Although I use Scapple for simple timelines, I also use Freeform for more complicated ones (almost like your examples.) See this Is Scapple usable as a timeline software? and a reply of mine: Using Freeform as a timeline app