Well that's hard to answer considering childhood development tends to go fast and also I was never a typically developing child. If I ever play as 1 it's mostly because I am stressed I am not happy(or at the very least not energetic) if I am 1 I mostly just need a nap I don't talk much or do much besides lie down and maybe watch some early learning shows or maybe read a story. Do 1 year olds only sleep? No of course not. Can they read? No of course not. But in my mind do certain feelings and behaviours get associated with numbers? Yes of course.
I had a phase of going through developmental charts and trying to perfectly match things up but considering I was delayed in my biological childhood relying on these for my headspaces was not particularly helpful. And I am of course an adult not a child so it could never be an even match anyway from a base level my brain just does not work that way at this point. Instead I have feelings and behaviours that in my mind match up.
1: sleepy, a little melancholy or possibly just content, slow in movement, I won't talk or even babble much, I won't eat solid food mostly just drink out of a bottle, I will use a pacifier, I may watch some cartoons of often noise overwhelms me more most likely due to being tired so I like to read stories on here or on other forums.
2-3: playful, shy, still not talking much to others but I will talk to myself, I like toys when at these ages so stuffies, blocks, stacker toys, slime, sand really anything I like, I love shows aimed at preschoolers like sesame street or really any puppet based shows seem to be where I gravitate or shows like ni hao kai lan or team umizoomi, I will eat but mostly finger food and I still love my bottles and sippy cups and pacifiers.
4-5: curious, talkative, social, if I am with my little friends I tend to go to this, I am more outgoing at this age I like to playfully tease others and I like to feel smart, I love doing art too lots of coloring and glueing things and making things pretty and shiny, I giggle a lot but I also tend to be a little more defiant, I like shows like sid the science kid, wild kratts and other older preschool shows with a focus on science I also like blind box opening. I am less interested in toys but I still love my stuffies and blocks, I also love music and dancing.
6: the unexplored one. I don't play as 6 much it's the only age were I don't use diapers and I honestly go back to being more quiet until somebody talks to me and I want to tell them all about whatever I am learning or doing, I am much more physically active I like running and jumping and dancing, playing board games,dress up, MLP and LPS, anything active and super girly, I love to organize all my collectables.
And yes of course lines blur and change as we all all in a state of flux at all times but I have given it lots of thought over quite a long time and these were the patterns that emerged.