D&D is NOT the right vehicle for this.
As veteran players, we have internalized all of the channels we are directed into, all the limitations and fetters on our creativity. But I go back to when my eldest first saw me making a D&D character, back in the 3ed (or 3.5) era and wanted to make one.
I asked her what type of character she wanted to play, and she came up with this rather long list that would have fit well in a fairy tale or story or cartoon, but was bits and bobs from more than half the classes and some things still couldn't be well covered.
So I worked with her for a while on narrowing it down to the most important to her, discarding most of her ideas, and we got to "turn into a cat" and "heal people". I explained about druid, and it had a bunch of unwanted baggage she didn't want and couldn't see herself using, but there really no other class options.
Then I went on to explain ability scores. After the description of what each was, she wanted her highest to be Dexterity so she could move like Peter Parker (not like Spider-man, but like Peter Parker), and she wanted her lowest to be Wisdom, because she wanted to be impulsive and carefree. How she envisioned the character had the primary ability score for the class as a dump stat.
In the end, we never built that Druid. D&D in no way was capable of mimicing a free-form character design for someone who wasn't ready to fit it into the grooves of what D&D allows. The classes are pre-packaged bundles that are not designed for freeform building, plus can contain abilities that aren't outside what the player wants. Linking certain ability scores to class features also locks concepts out.
D&D is a bad fit for non-D&D players coming up with freeform character concepts and then trying to realize them as starting characters.