Long live copy & paste
Cut and paste is one of the earliest computer terms I remember learning. It's a extremely simple concept, and has been extraordinarily powerful in making users more productive when editing text. The idea was first introduced in Apple's Lisa computer in 1983 after being developed by Tim Mott and Larry Tessler, who passed away earlier this year(https://www.theguardian.com/technology/2020/feb/20/creator-of-copy-and-paste-command-larry-tesler-dies-aged-74).
Back in a 3nd grade computer lab class, I recall being introduced to the concept and seeing the icons mimicking literal pasting with glue. It's hard to imagine a more used feature in word processing and this simple feature alone made it exponentially more powerful than a typewriter.
One of my personal favorite tools, Ditto, expands on classic copy and paste features by keeping a log of copied entries to later paste. Its saved me countless hours, and saved me dozens of otherwise lost backups.
Some of the most powerful features are extremely simple and can be integrated into routines easily. Copy and paste serves as such a great example that it often goes completely unnoticed, as the very best features typically do.