briefly: you should make an original character
There’s something fun and rewarding about creating a guy in your head to rotate for hours on end.
Having taken part in the online artist arena since the days of lying about my age on DeviantART, creating your own original characters was a fun facet of the artist experience at the time. I think a lot of it was just wish fulfillment - creating some funny little guy to live vicariously through as a rainbow-haired magical girl or a flashy one-winged warrior cat or what have you. Many of them were fandom-based, but there were also many self-contained OCs, too.
But it is an interesting thing to think about, because OCs are, intentionally or not, an extension of one’s self - it is through the OC that the creator expresses themself and their ideas, whether by itself or through the media the OC interacts with. Yeah, you may not be a 5’10 anime girlie with big honkers like the hypothetical OC I’ve given to you, but her ideals and thoughts are inherently influenced by your own. Maybe she likes beef burritos because you like beef burritos. Maybe she enjoys the same music you do. Maybe she’s also autistic and gay. Et cetera. And even if she couldn’t be farther from you, that character is still affected by you, as her creator - you deliberately chose to make her the way she is for reasons that are your own. Maybe you’re using her to explore literary concepts. Or maybe you’re using her for jerkoff material. She’s your oyster.
I do remember there being this widespread anxiety towards the idea of having what’s called a Mary Sue: this perfect character (typically targeted towards female characters with impunity, though there is a male equivalent, the Gary Stu) who does everything right and has no flaws. There’s been gallons of digital ink spilled on what they are, how to avoid creating them, what have you.
In a vacuum, it’s not without purpose: perfect characters who can do everything perfect and are perfect can be pretty boring to read about! Folks love a underdog story, watching some fella go through the wringer in their trials and tribulations. It’s a character’s negatives, their vices, combined with their positives and virtues and how they lead their lives through their own lens that make them interesting and relatable. But I also think the term itself has long been used less as a learning tool for writing and more as a cudgel against artists, predominantly younger or inexperienced creators, for making characters that are self-indulgent, cool for the sake of cool. There’s a great article by Springhole on this topic, and in relation to creating fictional characters. And like, yeah, your hypothetical sparkledog may be derivative and masturbatory, but - who cares? There are many characters across innumerable franchises and medias that would be considered Mary Sues or their equivalents, and they’re outright beloved.
I think, in the pursuit to create for the sake of creation’s sake, character creation serves as an important exercise in multiple forms - in storytelling (who is your character? what is their story?) and design (what do they look like? what aspects support their story?). Tabletop RPGs like DnD are fantastic examples of this, even if it’s a little cliche. Making a Guy and playing as that Guy is a core part of the experience.
And if nothing else, sometimes you just need to create a funny little creature to derive joy from. They don’t even necessarily need to be tied to a particular fandom or something special and fantastical. That creature can really be Just Some Guy. And they’d be yours!