Artist Winslow Homer would do sketch after sketch, study after study, before he did his final "one-off" masterpiece. Keep improving the idea. It is astonishing what serendipity that can occur.
Here is a visual example: Andy Warhol's skulls:
https://www.google.com/search?q=warhol+skull+collection&tbm=...
For another example, in information architecture, one way to do that is according to LATCH, which I've previously written about here: https://news.ycombinator.com/item?id=1554237
Another exercise is what I call "counterparts," what are all the ways other industries, other organizations, other people have solved this problem? And not just the problem as-is, but, when you simplify or abstract the problem, or you turn it into a process, or you approximate it into steps, how do those solutions go? Following a recipe in a cookbook feels very different from stepping through a software installation wizard, and yet they are both guiding us through a process.
Take the time to actually explore the entire possibility space. You can't get to the really crazy, novel solutions until you've thought through all the obvious ones. "If you didn't have to build it" and "if money and physics were no object" are valuable constraints.
Finally, spend your "inventive" energy where it matters, and don't value inventiveness for inventiveness' sake. Design has to serve masters: users, and business goals, and success metrics. If you're not testing your creative solutions against those and proving their value, then your "inventive" solution isn't any better than anyone else's "obvious" solution. An "obvious" solution that's cribbed from another industry but that tests out as a viable solution is way better than something super original that you have no idea how it's going to perform.
He was mostly interested in how exactly to develop a creativity trait, and came up with something called a "Theory of a Creative Personality Development", a further generalisation of TRIZ.
There are some anecdotal confirmations from various schools across the former USSR that this approach is known to produce some stable results. So at least it worth looking into.
There are just people who somehow know the creativity tricks (either deliberately learned or randomly discovered), and the "ordinary" people who happen to have a little gap in their education. Learning the formal approaches to creativity could help to close this gap.
Secondly, if simulating creativity is indistinguishable (by the outcome) from a "true" creativity, then the very existence of creativity is questionable, and it is likely that all forms of creativity can be explained by simply knowing (maybe subconsciously) a number of techniques of "simulating" the creativity.