People like me aren't that great at creating original content that is enjoyable.
You'd be surprised. Your party finds the "tank device" in your latest modern picture in a dungeon. What is it used for? Why is it there? Who built it? Does it smell? Does it make noise? Why does that window in it glow?
You can get creative just be continually asking "why" about some premise and making up an answer, even if the answer is not "original".
Farmers are missing. (not original)
Why?
Orc raiders killed them. (not original)
Why?
The orc had to raid farther than they normally do. (not very original)
Why?
Their local food supplies were low. (not very original)
Why?
A wyvern showed up and ate all the sheep in the lands around the orcs. (not original, a monster ate their food)
Why?
The wyvern had fled into the area after being attacked by adventurers in the next kingdom over. (aha! maybe that's original?)
The basic problem is farmers are missing. But asking why enough and your heroes are trying to deal with a wyvern that's just come into the area and whose presence has upset the local balance. It's a premise what would work for taking new characters up to level 3-4 or so, culminating in a fight with a wyvern or maybe some negotiations with an orc chieftain, so giving the party a suitable climactic encounter.
Players could kill the orcs, or kill the wyvern (allowing the sheep to repopulate, thus preventing the orcs from needing to raid so far away), or even get the wyvern to move along to somewhere else somehow or unite the orcs to get rid of the wyvern.
You can take a basic premise and repeat "why" until you have the desired level of detail.
/also constantly asking "why" is a great way to annoy your parents when you are a kid.