When I left work I decided to try to broaden my social circle in my home town (I worked a distance away), and I also found it wan't easy to find people in their 50s/60s who weren't working. I do have local friends, but I am more sociable than they are, and as we are something of a 'group', I wanted to do things with other people as well as with them.
I joined classes, but then Covid hit and they were cancelled. I started a group based on an interest of mine, and it is still going, but is not well attended, and will probably fold soon. We meet monthly, and I think a lot of people just don't want regular commitment. They want someone else to do the legwork, and to have things there when they fancy going out, but are very quick to pull out if it looks like rain, or if they get a better offer. As often as not there are not enough subs to pay the rent, and I can't go on subsidising it forever.
I even did another degree, but that was affected by Covid too, and when it finished the people I'd met moved back to their home towns. I am happy to travel into the city where I worked, but I don't drive, and it's far more of a hassle to do that when I'm coming in from home than it was when I was already there. I wasn't keen to use buses until recently (because of Covid) but I am a lot more confident about that now.
I joined the NWR and a knitting group, and have met some lovely people, but on the whole they are a fair bit older than me. I enjoy the meetings, but so far haven't met anyone I really want to meet up with outside of them, and anyway they are in established friendship groups with other interests. I think it's a case of keeping plugging away though. New people join things, and I am not going to get younger . In a while there will be people of my age coming to retirement, although as you say, I am far more concerned about attitudes than age. At work my friends tended to be younger than me, and I am still in touch with ex students who are more my children's ages than mine.
That's not much help, is it? . I can say that I empathise though, and that I haven't given up. I do a lot of online things (mostly classes on Zoom - check out Eventbrite to see if there is anything on offer that appeals to you) and have met people through those who share my interests. They are not local, but I have met a few when we've travelled to meet up, and now think of them as friends. the more you do online things the more it feels like meeting up - the strangeness does dissipate.
Do you live near where you grew up or went to university? If so, could you reconnect with old friends? I've done a bit of that, and added to the list of people I can call on to go for lunch or whatever. It's slow progress, but I think that Covid has slowed down social things for a lot of people, and that it will pic up as time goes by. Good luck!