I, too, never had the knack for creating a dungeon/adventure. I never seemed to have either time or inspiration or both. It’s likely keyed on my executive functioning issues with AD&D … oops ADHD and having trouble deciding between all the ideas and feeling overwhelmed.

I found that, after DMing (in person) for nearly 20 years back in the day - I was good enough to entertain and while I never truly wrote a dungeon, I totally wrote backstories to existing npcs and stuff to fit something about the party or that I wanted to do. Sometimes these stories were highlighted, sometimes they passed unlearned but always they helped me understand motivations and plans and I “winged it” much better than I expected due to this.

I also found much enjoyment in taking adventures and piecing them together in my own way. Changing aspects to make them a whole. Or when tired, and have a second game for the group that week (played Fri and often Sat), I’d grab a Dragon magazine module and Dungeon and maybe one some more obscure adventure fI had and place a preset piece, encounter or bar where clues happened or motivations triggered and folks picked the adventure of the night.

Then I did my modifications both before but MOSTLY after the night’s sessions. I’d made denizens or connected groups elsewhere REACT to the Pcs actions (not always representing something in the immediate - sometimes giving me an idea for a recurring villain or consequence in another adventure that entity was not in but now is. It gave them a sense of “lived in” and “things happening behind scenes”

I also just straight up change modules cos I like something about them but they are for a diff system or I read an article and wanted to try something or both. Like the time I transformed “Palace of Ontoncle” (Dragonquest) into an AD&D adventure where a large Kzinti family/war party were trapped in our world there and setup base in that environment. Changing many of the encounters found there and the overarch. It was definitely fun for me to run and most of my party didn’t read the animated Star Trek or Niven books like I did, so a lot of it was a new experience for them.

Running adventures doesn’t have to be all you creating it - though that is rewarding itself.

Also, to add to resources - Matt Finch of S&W/OSRIC wrote “Tome of Adventure Desigb” which is full of ideas and tables for generating stuff then with inspiration done taking it and tweaking it as you’d like. It is available at Froggodgames.com in the original years long used one and a new edition put out by him at mythmere games. It’s very close to the original with some tweaks like putting “inspiration words” all along the margins. It is a beautiful edition.