Nah I think that May is one of the MORE mature characters. She is just prickly sometimes. However, she does understand how the real world works, something that the comfortable income with very little effort that other cast members seem to have lack.
I can’t remotely agree with this. May comes across as a sociopathic child most of the time, a creature of pure Id that can’t imagine anyone else’s point of view mattering. Which is why her appearing contrite in her recent conversation with Momo was a first. I haven’t seen any evidence that she knows how the “real world works” beyond what has happened to her directly.
I don’t know where the “comfortable income” thing is coming from either. Marten basically has no money. Bubbles and Faye have frequently talked about how their shop is barely solvent. Dora talks about money problems all the time too, even if she does own Coffee of Doom. Most characters live with roommates because they can’t afford their own apartments. The main difference between May and the other barely making it characters is that May complains about it.
You might think Faye / Bubbles / Dora are relatively wealthy because they own businesses, but that’s not necessarily true. Some of the worst years my own life financially were when I was the co-owner of a small programming consultancy. I didn’t really get my life together financially until I got a regular salaried job.
The main exceptions financially are Hannelore and Sven. Hannelore was apparently slumming for her mental health. Basically getting away from her parents who are both hard to be around for different reasons. Sven’s so undeveloped we really don’t know much about him beyond what the other characters think about him.
What you said about Winslow and Momo is true enough. Winslow being a sweet child has been pretty much his thing the entire time, even when he was an old-style iPod. Momo used to be pretty adult, but that got dumped when she changed bodies, and now she’s pretty much a teenager the entire time.
If we’re going to talk emotionally mature... Bubbles is probably it. And maybe some of the older tertiary characters we don’t see that often, like Jim the owner of the Secret Bakery. Before the crisis between Dora and Marten I might have said Dora, but her behavior during the breakup pretty much blew that up for me.
EDIT: ... and Roko, come to think of it. I like Roko, and while she gets ticked (see today’s strip) now and then, she comes across as adult. Certainly more than Marten, Faye, or Dora.