Sorry, I haven't read through all posts (need to run)!
Just want to say, like others have pointed out:
The more you know about ND, the more you realise it's not "one" thing or "a few". That's why they call them "spectrums".
When my older one was diagnosed eventually at age 10, I was both worried and surprised to spot wordings like "traits within ASD spectrum". But gradually I realised there's always a bit overlap, because it's just how the brain is structured! I'm certainly not ASD but ADHD, but I think I do have some ASD traits myself and surprisingly my mum! Just a small fraction of it - you can name it as "the quirks" if not thinking too deeply.
I'm saying all these don't mean your child is ND, but I mean if you see how the brain is connected by different parts and elements, with billions of people, certainly one is different from the other. So it wouldn't be strange or unusual you find some so-called ASD traits are mildly presented in NT people. But the brains of NT people are "typical" enough to not hinder their developmental milestones or their normal pursuit of ordinary life - which ND children can't easily do without great help because their brains are sufficiently different making them not able to meet the "normal society standards".
Oh dear, I've been too wordy. But that's how I understand it.
Just googled it, first came up is this:
"We have shown that even in a non-referred, non-clinical population, participants with greater levels of autism-spectrum traits—which exist on a continuum even in neurotypical individuals—appear to show reduced grounding in motor experience of object-concept representations.25 Jul 2022
www.ncbi.nlm.nih.gov › pmc
Autism-spectrum traits in neurotypicals predict the embodiment of manipulation"
Just keep an eye, and if there are more symptoms show up, you reassess the situation. But from what you said, especially he's doing really well in school socially and academically, I don't think you need to worry. All kids are different and 5 years old is still very young.